[BUG] strands-agents 1.16.0 is incompatible with Pydantic > 2.11

[awerchniak]

Checks

• I have updated to the lastest minor and patch version of Strands
• I have checked the documentation and this is not expected behavior
• I have searched ./issues and there are no duplicates of my issue

Strands Version

1.16.0

Python Version

3.10.17

Operating System

macOS 15.6.1

Installation Method

pip

Steps to Reproduce

#1089 introduced differences to how types are interpreted for ToolSpecs. In nova-act, we have a few tools which are implemented via strands and which have typing.Literal argument types. See, specifically:

1. https://github.com/aws/nova-act/blob/9ea9851401bf5ee8223875f29fc17e3eb87d522f/src/nova_act/tools/browser/interface/browser.py#L75-L79
2. https://github.com/aws/nova-act/blob/9ea9851401bf5ee8223875f29fc17e3eb87d522f/src/nova_act/tools/browser/interface/types/click_types.py#L21

Following release of strands v1.16.0, users started seeing failures as follows:

pydantic.errors.PydanticUserError: `Agent_clickTool` is not fully defined; 
you should define `ClickType`, then call `Agent_clickTool.model_rebuild()`.

We were able to resolve the issue by either fixing the strands version to <=1.14.0 or by setting pydantic to <=pydantic==2.11.10.

However, it would be better if Strands support newer Pydantic versions.

See: aws/nova-act#79 for full information.

Expected Behavior

@tool works when passing a typing.Literal type and having Pydantic 2.12.0 installed

Actual Behavior

pydantic.errors.PydanticUserError: `Agent_clickTool` is not fully defined; 
you should define `ClickType`, then call `Agent_clickTool.model_rebuild()`.

Additional Context

No response

Possible Solution

No response

Related Issues

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