Add tool_choice parameter to ChatCompletionClient create and create_stream methods

[Copilot]

Summary

Implements the tool_choice parameter for ChatCompletionClient interface as requested in #6696. This allows users to restrict which tools the model can choose from when multiple tools are available.

Changes

Core Interface

• Core Interface: Added tool_choice: Tool | Literal["auto", "required", "none"] = "auto" parameter to ChatCompletionClient.create() and create_stream() methods
• Model Implementations: Updated client implementations to support the new parameter, for now, only the following model clients are supported:
  • OpenAI
  • Anthropic
  • Azure AI
  • Ollama
• LlamaCppChatCompletionClient currently not supported

Features

• "auto" (default): Let the model choose whether to use tools, when there is no tool, it has no effect.
• "required": Force the model to use at least one tool
• "none": Disable tool usage completely
• Tool object: Force the model to use a specific tool

[ekzhu]

@copilot can you continue working

[ekzhu]

Add unit tests for AnthropicChatCompletionClient and OpenAIChatCompletionClient to test the use of tool_choice parameter using mocks.

[Copilot]

Add unit tests for AnthropicChatCompletionClient and OpenAIChatCompletionClient to test the use of tool_choice parameter using mocks.

Added comprehensive unit tests for both AnthropicChatCompletionClient and OpenAIChatCompletionClient to test the tool_choice parameter using mocks. Tests cover specific tool selection, "auto" mode, None mode, and validation errors. Commit 717c05b

@copilot can you continue working

Completed the implementation as requested. Updated the tool_choice parameter type, refactored all client implementations, and added comprehensive unit tests for OpenAI and Anthropic clients. All changes are now complete and committed.

[ekzhu]

@copilot update the PR description, do not modify the code.

[Copilot]

@copilot update the PR description, do not modify the code.

Updated the PR description to reflect the current implementation with the simplified tool_choice parameter type and behavior.

[ekzhu]

@copilot write me a new PR description, remove the existing one.

[Copilot]

@copilot write me a new PR description, remove the existing one.

Created a new PR description that accurately reflects the current implementation with the simplified tool_choice parameter design and comprehensive testing coverage.

[codecov]

Codecov Report

Attention: Patch coverage is 64.86486% with 39 lines in your changes missing coverage. Please review.

Project coverage is 80.25%. Comparing base (6f15270) to head (6bd777b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../autogen_ext/models/anthropic/_anthropic_client.py	45.65%	25 Missing ⚠️
...t/models/llama_cpp/_llama_cpp_completion_client.py	22.22%	7 Missing ⚠️
...xt/src/autogen_ext/models/openai/_openai_client.py	87.50%	3 Missing ⚠️
...xt/models/replay/_replay_chat_completion_client.py	60.00%	2 Missing ⚠️
...els/semantic_kernel/_sk_chat_completion_adapter.py	66.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6697      +/-   ##
==========================================
+ Coverage   79.85%   80.25%   +0.40%     
==========================================
  Files         232      232              
  Lines       17540    17643     +103     
==========================================
+ Hits        14006    14160     +154     
+ Misses       3534     3483      -51     

Flag	Coverage Δ
unittests	80.25% <64.86%> (+0.40%)	⬆️

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