anthropic-beta and VertexAI

[ehaca]

Hello folks,

I've been having issues with using claude 3.7 Sonnet and 4 in the VertexAI model garten becasue of the default anthropic-beta headers (see liked line).

If I uncomment the line or set the default to NOT_GIVEN the agent works just fine. Since I am probably missing lots of context I didn't go ahead and opened a new PR removing the line, but if needed/wanted, I am totally open to it, just let me know.

pydantic-ai/pydantic_ai_slim/pydantic_ai/models/anthropic.py

Line 267 in 1c3999b

extra_headers.setdefault('anthropic-beta', 'code-execution-2025-05-22')

[Kludex]

How can I reproduce it?

[ehaca]

Being autenticated with the GCP and having the model activated:

from anthropic import AnthropicVertex, AsyncAnthropicVertex
from pydantic_ai.models.anthropic import AnthropicModel
from pydantic_ai.providers.anthropic import AnthropicProvider

anthropic_client = AsyncAnthropicVertex(
    project_id=<gcp_project_id>,
    region=<region>
)

claude_model = AnthropicModel("claude-3-7-sonnet", provider=AnthropicProvider(anthropic_client=anthropic_client))

agent = Agent(model=claude_model)
...

I got:

pydantic_ai.exceptions.ModelHTTPError: status_code: 400, model_name: claude-3-7-sonnet, body: {'type': 'error', 'error': {'type': 'invalid_request_error', 'message': 'Unexpected value(s) `code-execution-2025-05-22` for the `anthropic-beta` header. Please consult our documentation at docs.anthropic.com or try again without the header.'

[tuure-vincit]

I'm having the same issue. As a workaround, I provided empty anthropic-beta entry in extra_headers to the model settings (see code below). Providing the 'code-execution-2025-05-22' in extra headers probably shouldn't be the default behaviour, seeing how many models still in use do not support it. Or at least there should be a better way to disable it.

model = AnthropicModel(
    "claude-3-5-sonnet-v2@20241022",
    provider=AnthropicProvider(
        anthropic_client=AsyncAnthropicVertex(
            project_id="<project-id>",
            region="<region>",
        )
    ),
    settings=AnthropicModelSettings(extra_headers={"anthropic-beta": ""}),
)

[jerry-reevo]

Personally I feel like this should not be set by default and users should not have to explicitly set the anthropic-beta header to an empty string as a workaround.

It's also not obvious this is added to a user's Agent even when it's working.

I've opened a PR to remove it here: #2544

[ehaca]

I guess that might break this feature: https://ai.pydantic.dev/builtin-tools/

If the maintainers wish to change it would be happy to join and try to fix 🙂