diff --git a/example/convex/_generated/api.d.ts b/example/convex/_generated/api.d.ts
index 5ea46d86..aa9de768 100644
--- a/example/convex/_generated/api.d.ts
+++ b/example/convex/_generated/api.d.ts
@@ -347,6 +347,9 @@ export declare const components: {
                           }
                         | {
                             args: any;
+                            dynamic?: boolean;
+                            error?: any;
+                            invalid?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -362,6 +365,7 @@ export declare const components: {
                           }
                         | {
                             args?: any;
+                            dynamic?: boolean;
                             experimental_content?: Array<
                               | { text: string; type: "text" }
                               | {
@@ -387,6 +391,7 @@ export declare const components: {
                                       }
                                   >;
                                 };
+                            preliminary?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -439,6 +444,7 @@ export declare const components: {
               | {
                   content: Array<{
                     args?: any;
+                    dynamic?: boolean;
                     experimental_content?: Array<
                       | { text: string; type: "text" }
                       | { data: string; mimeType?: string; type: "image" }
@@ -456,6 +462,7 @@ export declare const components: {
                             | { data: string; mediaType: string; type: "media" }
                           >;
                         };
+                    preliminary?: boolean;
                     providerExecuted?: boolean;
                     providerMetadata?: Record<string, Record<string, any>>;
                     providerOptions?: Record<string, Record<string, any>>;
@@ -650,6 +657,9 @@ export declare const components: {
                           }
                         | {
                             args: any;
+                            dynamic?: boolean;
+                            error?: any;
+                            invalid?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -665,6 +675,7 @@ export declare const components: {
                           }
                         | {
                             args?: any;
+                            dynamic?: boolean;
                             experimental_content?: Array<
                               | { text: string; type: "text" }
                               | {
@@ -690,6 +701,7 @@ export declare const components: {
                                       }
                                   >;
                                 };
+                            preliminary?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -742,6 +754,7 @@ export declare const components: {
               | {
                   content: Array<{
                     args?: any;
+                    dynamic?: boolean;
                     experimental_content?: Array<
                       | { text: string; type: "text" }
                       | { data: string; mimeType?: string; type: "image" }
@@ -759,6 +772,7 @@ export declare const components: {
                             | { data: string; mediaType: string; type: "media" }
                           >;
                         };
+                    preliminary?: boolean;
                     providerExecuted?: boolean;
                     providerMetadata?: Record<string, Record<string, any>>;
                     providerOptions?: Record<string, Record<string, any>>;
@@ -971,6 +985,9 @@ export declare const components: {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -983,6 +1000,7 @@ export declare const components: {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -1004,6 +1022,7 @@ export declare const components: {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1047,6 +1066,7 @@ export declare const components: {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -1064,6 +1084,7 @@ export declare const components: {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
@@ -1276,6 +1297,9 @@ export declare const components: {
                           }
                         | {
                             args: any;
+                            dynamic?: boolean;
+                            error?: any;
+                            invalid?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -1291,6 +1315,7 @@ export declare const components: {
                           }
                         | {
                             args?: any;
+                            dynamic?: boolean;
                             experimental_content?: Array<
                               | { text: string; type: "text" }
                               | {
@@ -1316,6 +1341,7 @@ export declare const components: {
                                       }
                                   >;
                                 };
+                            preliminary?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -1368,6 +1394,7 @@ export declare const components: {
               | {
                   content: Array<{
                     args?: any;
+                    dynamic?: boolean;
                     experimental_content?: Array<
                       | { text: string; type: "text" }
                       | { data: string; mimeType?: string; type: "image" }
@@ -1385,6 +1412,7 @@ export declare const components: {
                             | { data: string; mediaType: string; type: "media" }
                           >;
                         };
+                    preliminary?: boolean;
                     providerExecuted?: boolean;
                     providerMetadata?: Record<string, Record<string, any>>;
                     providerOptions?: Record<string, Record<string, any>>;
@@ -1578,6 +1606,9 @@ export declare const components: {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1590,6 +1621,7 @@ export declare const components: {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -1611,6 +1643,7 @@ export declare const components: {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1654,6 +1687,7 @@ export declare const components: {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -1671,6 +1705,7 @@ export declare const components: {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
@@ -1851,6 +1886,9 @@ export declare const components: {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1863,6 +1901,7 @@ export declare const components: {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -1884,6 +1923,7 @@ export declare const components: {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1927,6 +1967,7 @@ export declare const components: {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -1944,6 +1985,7 @@ export declare const components: {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
@@ -2135,6 +2177,9 @@ export declare const components: {
                           }
                         | {
                             args: any;
+                            dynamic?: boolean;
+                            error?: any;
+                            invalid?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -2150,6 +2195,7 @@ export declare const components: {
                           }
                         | {
                             args?: any;
+                            dynamic?: boolean;
                             experimental_content?: Array<
                               | { text: string; type: "text" }
                               | {
@@ -2175,6 +2221,7 @@ export declare const components: {
                                       }
                                   >;
                                 };
+                            preliminary?: boolean;
                             providerExecuted?: boolean;
                             providerMetadata?: Record<
                               string,
@@ -2227,6 +2274,7 @@ export declare const components: {
               | {
                   content: Array<{
                     args?: any;
+                    dynamic?: boolean;
                     experimental_content?: Array<
                       | { text: string; type: "text" }
                       | { data: string; mimeType?: string; type: "image" }
@@ -2244,6 +2292,7 @@ export declare const components: {
                             | { data: string; mediaType: string; type: "media" }
                           >;
                         };
+                    preliminary?: boolean;
                     providerExecuted?: boolean;
                     providerMetadata?: Record<string, Record<string, any>>;
                     providerOptions?: Record<string, Record<string, any>>;
@@ -2362,6 +2411,9 @@ export declare const components: {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -2374,6 +2426,7 @@ export declare const components: {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -2395,6 +2448,7 @@ export declare const components: {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -2438,6 +2492,7 @@ export declare const components: {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -2455,6 +2510,7 @@ export declare const components: {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
diff --git a/src/UIMessages.ts b/src/UIMessages.ts
index 8e6fddaa..7a3d15ba 100644
--- a/src/UIMessages.ts
+++ b/src/UIMessages.ts
@@ -381,10 +381,9 @@ function createAssistantUIMessage<
   const allParts: UIMessage<METADATA, DATA_PARTS, TOOLS>["parts"] = [];
 
   for (const message of group) {
-    const coreMessage = message.message && toModelMessage(message.message);
-    if (!coreMessage) continue;
+    if (!message.message) continue;
 
-    const content = coreMessage.content;
+    const content = message.message.content;
     const nonStringContent =
       content && typeof content !== "string" ? content : [];
     const text = extractTextFromMessageDoc(message);
@@ -441,12 +440,11 @@ function createAssistantUIMessage<
             type: "step-start",
           } satisfies StepStartUIPart);
           const toolPart: ToolUIPart<TOOLS> = {
+            ...omit(contentPart, ["args", "type"]),
             type: `tool-${contentPart.toolName as keyof TOOLS & string}`,
-            toolCallId: contentPart.toolCallId,
-            input: contentPart.input as DeepPartial<
+            input: contentPart.args as DeepPartial<
               TOOLS[keyof TOOLS & string]["input"]
             >,
-            providerExecuted: contentPart.providerExecuted,
             ...(message.streaming
               ? { state: "input-streaming" }
               : {
@@ -459,9 +457,9 @@ function createAssistantUIMessage<
         }
         case "tool-result": {
           const output =
-            contentPart.output?.type === "json"
+            typeof contentPart.output?.type === "string"
               ? contentPart.output.value
-              : contentPart.output;
+              : (contentPart.output ?? contentPart.result);
           const call = allParts.find(
             (part) =>
               part.type === `tool-${contentPart.toolName}` &&
@@ -478,25 +476,22 @@ function createAssistantUIMessage<
               call.output = output;
             }
           } else {
-            console.warn(
-              "Tool result without preceding tool call.. adding anyways",
-              contentPart,
-            );
             if (message.error) {
               allParts.push({
+                input: contentPart.args,
+                ...omit(contentPart, ["args", "type", "output"]),
                 type: `tool-${contentPart.toolName}`,
-                toolCallId: contentPart.toolCallId,
                 state: "output-error",
-                input: undefined,
+                output,
                 errorText: message.error,
                 callProviderMetadata: message.providerMetadata,
               } satisfies ToolUIPart<TOOLS>);
             } else {
               allParts.push({
+                input: contentPart.args,
+                ...omit(contentPart, ["args", "type", "output"]),
                 type: `tool-${contentPart.toolName}`,
-                toolCallId: contentPart.toolCallId,
                 state: "output-available",
-                input: undefined,
                 output,
                 callProviderMetadata: message.providerMetadata,
               } satisfies ToolUIPart<TOOLS>);
diff --git a/src/client/index.ts b/src/client/index.ts
index 076cbcf1..682d7bae 100644
--- a/src/client/index.ts
+++ b/src/client/index.ts
@@ -1,7 +1,8 @@
-import type {
-  FlexibleSchema,
-  IdGenerator,
-  InferSchema,
+import {
+  getErrorMessage,
+  type FlexibleSchema,
+  type IdGenerator,
+  type InferSchema,
 } from "@ai-sdk/provider-utils";
 import type {
   CallSettings,
@@ -537,7 +538,7 @@ export class Agent<
       };
       return Object.assign(result, metadata);
     } catch (error) {
-      await call.fail(errorToString(error));
+      await call.fail(getErrorMessage(error));
       throw error;
     }
   }
@@ -642,8 +643,8 @@ export class Agent<
       ),
       onError: async (error) => {
         console.error("onError", error);
-        await call.fail(errorToString(error.error));
-        await streamer?.fail(errorToString(error.error));
+        await call.fail(getErrorMessage(error.error));
+        await streamer?.fail(getErrorMessage(error.error));
         return streamTextArgs.onError?.(error);
       },
       prepareStep: async (options) => {
@@ -743,7 +744,7 @@ export class Agent<
       };
       return Object.assign(result, metadata);
     } catch (error) {
-      await fail(errorToString(error));
+      await fail(getErrorMessage(error));
       throw error;
     }
   }
@@ -797,7 +798,7 @@ export class Agent<
         console.error(" streamObject onError", error);
         // TODO: content that we have so far
         // content: stream.fullStream.
-        await fail(errorToString(error.error));
+        await fail(getErrorMessage(error.error));
         return args.onError?.(error);
       },
       onFinish: async (result) => {
@@ -1668,10 +1669,3 @@ async function willContinue(
   }
   return !!stopWhen && !(await stopWhen({ steps }));
 }
-
-function errorToString(error: unknown): string {
-  if (error instanceof Error) {
-    return error.message;
-  }
-  return String(error);
-}
diff --git a/src/client/streaming.ts b/src/client/streaming.ts
index 23449a47..d72f0159 100644
--- a/src/client/streaming.ts
+++ b/src/client/streaming.ts
@@ -24,6 +24,7 @@ import type {
   RunQueryCtx,
   SyncStreamsReturnValue,
 } from "./types.js";
+import { getErrorMessage } from "@ai-sdk/provider-utils";
 
 export const vStreamMessagesReturnValue = v.object({
   ...vPaginationResult(vMessageDoc).fields,
@@ -312,9 +313,7 @@ export class DeltaStreamer<T> {
         return;
       }
     } catch (e) {
-      await this.config.onAsyncAbort(
-        e instanceof Error ? e.message : "unknown error",
-      );
+      await this.config.onAsyncAbort(getErrorMessage(e));
       this.abortController.abort();
       throw e;
     }
diff --git a/src/component/_generated/api.d.ts b/src/component/_generated/api.d.ts
index 3257e2f7..7cb89b2a 100644
--- a/src/component/_generated/api.d.ts
+++ b/src/component/_generated/api.d.ts
@@ -232,6 +232,9 @@ export type Mounts = {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -244,6 +247,7 @@ export type Mounts = {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -265,6 +269,7 @@ export type Mounts = {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -308,6 +313,7 @@ export type Mounts = {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -325,6 +331,7 @@ export type Mounts = {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
@@ -494,6 +501,9 @@ export type Mounts = {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -506,6 +516,7 @@ export type Mounts = {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -527,6 +538,7 @@ export type Mounts = {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -570,6 +582,7 @@ export type Mounts = {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -587,6 +600,7 @@ export type Mounts = {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
@@ -777,6 +791,9 @@ export type Mounts = {
                       }
                     | {
                         args: any;
+                        dynamic?: boolean;
+                        error?: any;
+                        invalid?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -786,6 +803,7 @@ export type Mounts = {
                       }
                     | {
                         args?: any;
+                        dynamic?: boolean;
                         experimental_content?: Array<
                           | { text: string; type: "text" }
                           | { data: string; mimeType?: string; type: "image" }
@@ -807,6 +825,7 @@ export type Mounts = {
                                   }
                               >;
                             };
+                        preliminary?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -841,6 +860,7 @@ export type Mounts = {
           | {
               content: Array<{
                 args?: any;
+                dynamic?: boolean;
                 experimental_content?: Array<
                   | { text: string; type: "text" }
                   | { data: string; mimeType?: string; type: "image" }
@@ -858,6 +878,7 @@ export type Mounts = {
                         | { data: string; mediaType: string; type: "media" }
                       >;
                     };
+                preliminary?: boolean;
                 providerExecuted?: boolean;
                 providerMetadata?: Record<string, Record<string, any>>;
                 providerOptions?: Record<string, Record<string, any>>;
@@ -1049,6 +1070,9 @@ export type Mounts = {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1061,6 +1085,7 @@ export type Mounts = {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -1082,6 +1107,7 @@ export type Mounts = {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1125,6 +1151,7 @@ export type Mounts = {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -1142,6 +1169,7 @@ export type Mounts = {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
@@ -1313,6 +1341,9 @@ export type Mounts = {
                       }
                     | {
                         args: any;
+                        dynamic?: boolean;
+                        error?: any;
+                        invalid?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -1322,6 +1353,7 @@ export type Mounts = {
                       }
                     | {
                         args?: any;
+                        dynamic?: boolean;
                         experimental_content?: Array<
                           | { text: string; type: "text" }
                           | { data: string; mimeType?: string; type: "image" }
@@ -1343,6 +1375,7 @@ export type Mounts = {
                                   }
                               >;
                             };
+                        preliminary?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -1377,6 +1410,7 @@ export type Mounts = {
           | {
               content: Array<{
                 args?: any;
+                dynamic?: boolean;
                 experimental_content?: Array<
                   | { text: string; type: "text" }
                   | { data: string; mimeType?: string; type: "image" }
@@ -1394,6 +1428,7 @@ export type Mounts = {
                         | { data: string; mediaType: string; type: "media" }
                       >;
                     };
+                preliminary?: boolean;
                 providerExecuted?: boolean;
                 providerMetadata?: Record<string, Record<string, any>>;
                 providerOptions?: Record<string, Record<string, any>>;
@@ -1556,6 +1591,9 @@ export type Mounts = {
                       }
                     | {
                         args: any;
+                        dynamic?: boolean;
+                        error?: any;
+                        invalid?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -1565,6 +1603,7 @@ export type Mounts = {
                       }
                     | {
                         args?: any;
+                        dynamic?: boolean;
                         experimental_content?: Array<
                           | { text: string; type: "text" }
                           | { data: string; mimeType?: string; type: "image" }
@@ -1586,6 +1625,7 @@ export type Mounts = {
                                   }
                               >;
                             };
+                        preliminary?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -1620,6 +1660,7 @@ export type Mounts = {
           | {
               content: Array<{
                 args?: any;
+                dynamic?: boolean;
                 experimental_content?: Array<
                   | { text: string; type: "text" }
                   | { data: string; mimeType?: string; type: "image" }
@@ -1637,6 +1678,7 @@ export type Mounts = {
                         | { data: string; mediaType: string; type: "media" }
                       >;
                     };
+                preliminary?: boolean;
                 providerExecuted?: boolean;
                 providerMetadata?: Record<string, Record<string, any>>;
                 providerOptions?: Record<string, Record<string, any>>;
@@ -1807,6 +1849,9 @@ export type Mounts = {
                         }
                       | {
                           args: any;
+                          dynamic?: boolean;
+                          error?: any;
+                          invalid?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1819,6 +1864,7 @@ export type Mounts = {
                         }
                       | {
                           args?: any;
+                          dynamic?: boolean;
                           experimental_content?: Array<
                             | { text: string; type: "text" }
                             | { data: string; mimeType?: string; type: "image" }
@@ -1840,6 +1886,7 @@ export type Mounts = {
                                     }
                                 >;
                               };
+                          preliminary?: boolean;
                           providerExecuted?: boolean;
                           providerMetadata?: Record<
                             string,
@@ -1883,6 +1930,7 @@ export type Mounts = {
             | {
                 content: Array<{
                   args?: any;
+                  dynamic?: boolean;
                   experimental_content?: Array<
                     | { text: string; type: "text" }
                     | { data: string; mimeType?: string; type: "image" }
@@ -1900,6 +1948,7 @@ export type Mounts = {
                           | { data: string; mediaType: string; type: "media" }
                         >;
                       };
+                  preliminary?: boolean;
                   providerExecuted?: boolean;
                   providerMetadata?: Record<string, Record<string, any>>;
                   providerOptions?: Record<string, Record<string, any>>;
@@ -2000,6 +2049,9 @@ export type Mounts = {
                       }
                     | {
                         args: any;
+                        dynamic?: boolean;
+                        error?: any;
+                        invalid?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -2009,6 +2061,7 @@ export type Mounts = {
                       }
                     | {
                         args?: any;
+                        dynamic?: boolean;
                         experimental_content?: Array<
                           | { text: string; type: "text" }
                           | { data: string; mimeType?: string; type: "image" }
@@ -2030,6 +2083,7 @@ export type Mounts = {
                                   }
                               >;
                             };
+                        preliminary?: boolean;
                         providerExecuted?: boolean;
                         providerMetadata?: Record<string, Record<string, any>>;
                         providerOptions?: Record<string, Record<string, any>>;
@@ -2064,6 +2118,7 @@ export type Mounts = {
           | {
               content: Array<{
                 args?: any;
+                dynamic?: boolean;
                 experimental_content?: Array<
                   | { text: string; type: "text" }
                   | { data: string; mimeType?: string; type: "image" }
@@ -2081,6 +2136,7 @@ export type Mounts = {
                         | { data: string; mediaType: string; type: "media" }
                       >;
                     };
+                preliminary?: boolean;
                 providerExecuted?: boolean;
                 providerMetadata?: Record<string, Record<string, any>>;
                 providerOptions?: Record<string, Record<string, any>>;
diff --git a/src/mapping.ts b/src/mapping.ts
index b37264b4..de674113 100644
--- a/src/mapping.ts
+++ b/src/mapping.ts
@@ -35,6 +35,8 @@ import {
   type vToolResultPart,
   type SourcePart,
   vToolResultOutput,
+  vAssistantContent,
+  vToolContent,
 } from "./validators.js";
 import type { ActionCtx, AgentComponent } from "./client/types.js";
 import type { RunMutationCtx } from "./client/types.js";
@@ -45,12 +47,15 @@ import {
   type ProviderOptions,
   type ReasoningPart,
 } from "@ai-sdk/provider-utils";
+import { type LanguageModelV2ToolResultOutput } from "@ai-sdk/provider";
 import { parse, validate } from "convex-helpers/validators";
 import {
+  extractText,
   getModelName,
   getProviderName,
   type ModelOrMetadata,
 } from "./shared.js";
+import { omit, pick } from "convex-helpers";
 export type AIMessageWithoutId = Omit<AIMessage, "id">;
 
 export type SerializeUrlsAndUint8Arrays<T> = T extends URL
@@ -98,9 +103,7 @@ export function fromModelMessage(message: ModelMessage): Message {
   return {
     role: message.role,
     content,
-    ...(message.providerOptions
-      ? { providerOptions: message.providerOptions }
-      : {}),
+    ...pick(message, ["providerOptions"]),
   } as SerializedMessage;
 }
 
@@ -117,9 +120,7 @@ export async function serializeOrThrow(
   return {
     role: message.role,
     content,
-    ...(message.providerOptions
-      ? { providerOptions: message.providerOptions }
-      : {}),
+    ...pick(message, ["providerOptions"]),
   } as SerializedMessage;
 }
 
@@ -179,38 +180,67 @@ export async function serializeNewMessagesInStep<TOOLS extends ToolSet>(
   step: StepResult<TOOLS>,
   model: ModelOrMetadata | undefined,
 ): Promise<{ messages: MessageWithMetadata[] }> {
-  // If there are tool results, there's another message with the tool results
-  // ref: https://github.com/vercel/ai/blob/main/packages/ai/core/generate-text/to-response-messages.ts
-  const assistantFields = {
-    model: model ? getModelName(model) : undefined,
-    provider: model ? getProviderName(model) : undefined,
-    providerMetadata: step.providerMetadata,
-    reasoning: step.reasoningText,
-    reasoningDetails: step.reasoning,
-    usage: serializeUsage(step.usage),
-    warnings: serializeWarnings(step.warnings),
-    finishReason: step.finishReason,
-    // Only store the sources on one message
-    sources: step.toolResults.length === 0 ? step.sources : undefined,
-  } satisfies Omit<MessageWithMetadata, "message" | "text" | "fileIds">;
-  const toolFields = { sources: step.sources };
-  const messages: MessageWithMetadata[] = await Promise.all(
-    (step.toolResults.length > 0
-      ? step.response.messages.slice(-2)
-      : step.content.length
-        ? step.response.messages.slice(-1)
-        : [{ role: "assistant" as const, content: [] }]
-    ).map(async (msg): Promise<MessageWithMetadata> => {
-      const { message, fileIds } = await serializeMessage(ctx, component, msg);
-      return parse(vMessageWithMetadata, {
-        message,
-        ...(message.role === "tool" ? toolFields : assistantFields),
-        text: step.text,
-        fileIds,
-      });
-    }),
+  const toolResultIndex = step.content.findIndex(
+    (c) =>
+      (c.type === "tool-result" || c.type === "tool-error") &&
+      !c.providerExecuted,
+  );
+  const hasToolResults = toolResultIndex !== -1;
+  const assistantContent = hasToolResults
+    ? step.content.slice(0, toolResultIndex)
+    : step.content;
+  const { content, fileIds } = await serializeStepContent(
+    ctx,
+    component,
+    assistantContent,
   );
-  // TODO: capture step.files separately?
+  const message = {
+    role: "assistant" as const,
+    content: content as Infer<typeof vAssistantContent>,
+    providerOptions: (hasToolResults
+      ? step.response.messages.at(-2)
+      : step.response.messages.at(-1)
+    )?.providerOptions,
+  } satisfies Message;
+  const messages = [
+    parse(vMessageWithMetadata, {
+      model: model ? getModelName(model) : undefined,
+      provider: model ? getProviderName(model) : undefined,
+      providerMetadata: step.providerMetadata,
+      reasoning: step.reasoningText,
+      reasoningDetails: step.reasoning,
+      usage: serializeUsage(step.usage),
+      warnings: serializeWarnings(step.warnings),
+      finishReason: step.finishReason,
+      fileIds,
+      // Only store the sources on one message
+      sources: assistantContent.filter((c) => c.type === "source"),
+      message,
+      text: extractText(message) || step.text,
+    }),
+  ];
+
+  if (hasToolResults) {
+    const toolContent = step.content.slice(toolResultIndex);
+    const { content, fileIds } = await serializeStepContent(
+      ctx,
+      component,
+      toolContent,
+    );
+    const toolMessage = {
+      role: "tool" as const,
+      content: content as Infer<typeof vToolContent>,
+      providerOptions: step.response.messages.at(-1)?.providerOptions,
+    } satisfies Message;
+    messages.push(
+      parse(vMessageWithMetadata, {
+        message: toolMessage,
+        sources: toolContent.filter((c) => c.type === "source"),
+        fileIds,
+        finishReason: step.finishReason,
+      }),
+    );
+  }
   return { messages };
 }
 
@@ -253,6 +283,129 @@ function getMimeOrMediaType(part: { mediaType?: string; mimeType?: string }) {
   return undefined;
 }
 
+export async function serializeStepContent(
+  ctx: ActionCtx,
+  component: AgentComponent,
+  content: StepResult<ToolSet>["content"],
+): Promise<{ content: SerializedContent; fileIds?: string[] }> {
+  const fileIds: string[] = [];
+  const serialized = await Promise.all(
+    content.map(async (part) => {
+      const metadata: {
+        providerOptions?: ProviderOptions;
+        providerMetadata?: ProviderMetadata;
+      } = {};
+      if ("providerOptions" in part) {
+        metadata.providerOptions = part.providerOptions as ProviderOptions;
+      } else if ("providerMetadata" in part) {
+        metadata.providerMetadata = part.providerMetadata;
+      }
+      switch (part.type) {
+        case "text": {
+          return part satisfies Infer<typeof vTextPart>;
+        }
+        case "reasoning":
+          return part satisfies Infer<typeof vReasoningPart>;
+        case "source":
+          return part satisfies Infer<typeof vSourcePart>;
+        case "tool-call": {
+          return {
+            ...pick(part, [
+              "type",
+              "toolCallId",
+              "toolName",
+              "providerExecuted",
+              "dynamic",
+              "error",
+              "invalid",
+            ]),
+            args: part.input,
+            ...metadata,
+          } satisfies Infer<typeof vToolCallPart>;
+        }
+        case "tool-result": {
+          const rawOutput = part.output;
+          const output: LanguageModelV2ToolResultOutput =
+            typeof rawOutput === "string"
+              ? { type: "text", value: rawOutput }
+              : { type: "json", value: part.output ?? null };
+
+          return {
+            ...pick(part, [
+              "type",
+              "toolCallId",
+              "toolName",
+              "dynamic",
+              "preliminary",
+              "providerExecuted",
+            ]),
+            args: part.input,
+            output,
+            ...metadata,
+          } satisfies Infer<typeof vToolResultPart>;
+        }
+        case "tool-error":
+          return {
+            ...pick(part, [
+              "toolCallId",
+              "toolName",
+              "dynamic",
+              "providerExecuted",
+            ]),
+            type: "tool-result",
+            args: part.input,
+            output:
+              part.error instanceof Error
+                ? {
+                    type: "error-text",
+                    value: part.error.message,
+                  }
+                : typeof part.error === "string"
+                  ? {
+                      type: "error-text",
+                      value: part.error,
+                    }
+                  : {
+                      type: "error-json",
+                      value: part.error ?? null,
+                    },
+            ...metadata,
+          } satisfies Infer<typeof vToolResultPart>;
+        case "file": {
+          const uint8Array = part.file.uint8Array;
+          let data: ArrayBuffer | string = uint8Array.buffer.slice(
+            uint8Array.byteOffset,
+            uint8Array.byteOffset + uint8Array.byteLength,
+          ) as ArrayBuffer;
+          const mimeType = getMimeOrMediaType(part.file)!;
+          if (data.byteLength > MAX_FILE_SIZE) {
+            const { file } = await storeFile(
+              ctx,
+              component,
+              new Blob([data], { type: mimeType }),
+            );
+            data = file.url;
+            fileIds.push(file.fileId);
+          }
+          return {
+            type: part.type,
+            data,
+            mimeType,
+            ...metadata,
+          } satisfies Infer<typeof vFilePart>;
+        }
+
+        default:
+          return part satisfies Infer<typeof vContent>;
+      }
+    }),
+  );
+  return {
+    content: serialized as SerializedContent,
+    fileIds: fileIds.length > 0 ? fileIds : undefined,
+  };
+}
+
 export async function serializeContent(
   ctx: ActionCtx | RunMutationCtx,
   component: AgentComponent,
@@ -463,20 +616,20 @@ export function toModelMessageContent(
           mediaType: getMimeOrMediaType(part)!,
           ...metadata,
         } satisfies FilePart;
-      case "tool-call": {
-        const input = "input" in part ? part.input : part.args;
+      case "tool-call":
         return {
-          type: part.type,
-          input: input ?? null,
-          toolCallId: part.toolCallId,
-          toolName: part.toolName,
-          providerExecuted: part.providerExecuted,
-          ...metadata,
+          input: ("input" in part ? part.input : part.args) ?? null,
+          ...omit(part as Infer<typeof vToolCallPart>, ["args"]),
         } satisfies ToolCallPart;
-      }
-      case "tool-result": {
-        return normalizeToolResult(part, metadata);
-      }
+      case "tool-result":
+        return {
+          input: (part as Infer<typeof vToolResultPart>).args,
+          output: normalizeToolOutput(
+            (part as Infer<typeof vToolResultPart>).result,
+          ),
+          ...omit(part as Infer<typeof vToolResultPart>, ["result", "args"]),
+          ...metadata,
+        } satisfies ToolResultPart & { input: unknown };
       case "reasoning":
         return {
           type: part.type,
@@ -534,16 +687,13 @@ function normalizeToolResult(
     providerOptions?: ProviderOptions;
     providerMetadata?: ProviderMetadata;
   },
-): ToolResultPart & Infer<typeof vToolResultPart> {
+): ToolResultPart & Infer<typeof vToolResultPart> & { input: unknown } {
   return {
-    type: part.type,
-    output:
-      part.output ??
-      normalizeToolOutput("result" in part ? part.result : undefined),
-    toolCallId: part.toolCallId,
-    toolName: part.toolName,
+    input: (part as Infer<typeof vToolResultPart>).args,
+    output: normalizeToolOutput("result" in part ? part.result : undefined),
+    ...omit(part as Infer<typeof vToolResultPart>, ["result", "args"]),
     ...metadata,
-  } satisfies ToolResultPart;
+  } satisfies ToolResultPart & { input: unknown };
 }
 
 /**
@@ -654,37 +804,26 @@ export function toModelMessageDataOrUrl(
   return urlOrString;
 }
 
-export function toUIFilePart(part: ImagePart | FilePart): FileUIPart {
+export function toUIFilePart(
+  part:
+    | ImagePart
+    | FilePart
+    | Infer<typeof vImagePart>
+    | Infer<typeof vFilePart>,
+): FileUIPart {
   const dataOrUrl = part.type === "image" ? part.image : part.data;
   const url =
     dataOrUrl instanceof ArrayBuffer
       ? convertUint8ArrayToBase64(new Uint8Array(dataOrUrl))
       : dataOrUrl.toString();
 
+  const mediaType = getMimeOrMediaType(part);
+
   return {
     type: "file",
-    mediaType: part.mediaType!,
+    mediaType: mediaType!,
     filename: part.type === "file" ? part.filename : undefined,
     url,
     providerMetadata: part.providerOptions,
   };
 }
-
-// Currently unused
-// export function toModelMessages(args: {
-//   messages?: ModelMessage[] | AIMessageWithoutId[];
-// }): ModelMessage[] {
-//   const messages: ModelMessage[] = [];
-//   if (args.messages) {
-//     if (
-//       args.messages.every(
-//         (m) => typeof m === "object" && m !== null && "parts" in m,
-//       )
-//     ) {
-//       messages.push(...convertToModelMessages(args.messages));
-//     } else {
-//       messages.push(...modelMessageSchema.array().parse(args.messages));
-//     }
-//   }
-//   return messages;
-// }
diff --git a/src/toUIMessages.test.ts b/src/toUIMessages.test.ts
index 8648a7b4..5dfc8452 100644
--- a/src/toUIMessages.test.ts
+++ b/src/toUIMessages.test.ts
@@ -132,10 +132,7 @@ describe("toUIMessages", () => {
       type: "tool-myTool",
       toolCallId: "call1",
       state: "output-available",
-      output: {
-        type: "text",
-        value: "42",
-      },
+      output: "42",
     });
   });
 
@@ -252,7 +249,7 @@ describe("toUIMessages", () => {
               type: "tool-result",
               toolName: "myTool",
               toolCallId: "call1",
-              result: {
+              output: {
                 type: "json",
                 value: { data: "wrapped result", success: true },
               },
@@ -648,10 +645,7 @@ describe("toUIMessages", () => {
       toolCallId: "call1",
       state: "output-available",
       input: { operation: "add", a: 40, b: 2 },
-      output: {
-        type: "text",
-        value: "42",
-      },
+      output: "42",
     });
 
     // Should also have text part
diff --git a/src/validators.ts b/src/validators.ts
index bac67a1b..a152af37 100644
--- a/src/validators.ts
+++ b/src/validators.ts
@@ -114,8 +114,11 @@ export const vToolCallPart = v.object({
   type: v.literal("tool-call"),
   toolCallId: v.string(),
   toolName: v.string(),
-  args: v.any(),
+  args: v.any(), // referred to as input in ai v5
   providerExecuted: v.optional(v.boolean()),
+  dynamic: v.optional(v.boolean()),
+  invalid: v.optional(v.boolean()),
+  error: v.optional(v.any()),
   providerOptions,
   providerMetadata,
 });
@@ -159,14 +162,18 @@ export const vToolResultPart = v.object({
 
   providerOptions,
   providerMetadata,
+  // In a modelMessage this is redundant with the call & stripped
+  // Referred to as input in ai v5
+  args: v.optional(v.any()),
   providerExecuted: v.optional(v.boolean()),
+  dynamic: v.optional(v.boolean()),
+  preliminary: v.optional(v.boolean()),
 
   // Deprecated in ai v5
   result: v.optional(v.any()), // either this or output will be present
   isError: v.optional(v.boolean()),
   // This is only here b/c steps include it in toolResults
   // Normal ModelMessage doesn't have this
-  args: v.optional(v.any()),
   experimental_content: v.optional(vToolResultContent),
 });
 export const vToolContent = v.array(vToolResultPart);