fix(bedrock): fall back to toolChoice.auto when model does not support toolChoice.any#2075
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…t toolChoice.any The Bedrock Converse API only supports toolChoice.any for Anthropic Claude models. Other families (Meta Llama, Amazon Titan/Nova, Mistral, Cohere) reject it with ValidationException. When structured output enters forced mode it sends toolChoice.any, causing crashes on non-Claude Bedrock models. Add _resolve_tool_choice to BedrockModel that detects support via _MODELS_SUPPORT_TOOL_CHOICE_ANY and falls back to toolChoice.auto with a warning log for unsupported models. Follows the existing _MODELS_INCLUDE_STATUS pattern in the file. Fixes strands-agents#1241
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Description
When the structured output context enters forced mode it sets
tool_choice = {"any": {}}torequire the model to call the structured output tool.
BedrockModel._format_requestforwardedthis directly as
toolConfig.toolChoice.anyto the Bedrock Converse API.The Bedrock Converse API only supports
toolChoice.anyfor Anthropic Claude models. All othermodel families — Meta Llama, Amazon Titan/Nova, Mistral, Cohere — reject it with a
ValidationException: This model doesn't support the toolConfig.toolChoice.any field.The fix adds a
_resolve_tool_choicehelper toBedrockModelthat detects whether the activemodel supports
toolChoice.anyand falls back totoolChoice.autowhen it does not. The modellist follows the existing
_MODELS_INCLUDE_STATUSpattern already used in the file.Related Issues
Fixes #1241
Documentation PR
N/A
Type of Change
Bug fix
Testing
How have you tested the change?
hatch run preparetest_format_request_tool_choice_anyusing a Claude model ID to verifytoolChoice.anypasses through unchangedtest_format_request_tool_choice_any_falls_back_for_unsupported_modelsusing a non-Claude model ID to verify fallback totoolChoice.autoChecklist
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