Add MCP builder support for output/error and caller-supplied item IDs

[Hameedkunkanoor]

This PR adds missing typed MCP streaming surface in azure-ai-agentserver-responses so hosted MCP relay flows can persist canonical completed mcp_call items.

Changes made

• Added optional item_id to add_output_item_mcp_call(...) so callers can preserve original MCP ids.
• Added optional output and error to OutputItemMcpCallBuilder.emit_done(...) so completed MCP items can carry final tool output/error.
• Added/updated unit tests for:
  • caller-supplied MCP item id
  • emit_done(output=..., error=...)
  • return-type expectations for the new MCP builder shape

Why this change

• Hosted MCP relay persistence requires a canonical completed mcp_call item containing call id, call arguments, and final output/error.
• Before this PR, typed surfaces could not preserve caller id and final output/error together.

Breaking change assessment

• No breaking changes.
• API changes are additive with optional parameters and backward-compatible defaults.

Testing

• Working directory:

   Code/azure-sdk-for-python/sdk/agentserver/azure-ai-agentserver-responses
  

• Command:

   python -m pytest tests/unit/test_builders.py tests/unit/test_emit_return_types.py -q
  

• Result:

   86 passed
  

Files changed

• sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/streaming/_builders/_tools.py
• sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/streaming/_event_stream.py
• sdk/agentserver/azure-ai-agentserver-responses/tests/unit/test_builders.py
• sdk/agentserver/azure-ai-agentserver-responses/tests/unit/test_emit_return_types.py

---

All SDK Contribution checklist

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds missing typed MCP streaming capabilities so hosted MCP relay flows can persist canonical completed mcp_call output items with stable IDs and final output/error payloads.

Changes:

• Added optional caller-supplied item_id to ResponseEventStream.add_output_item_mcp_call(...).
• Extended OutputItemMcpCallBuilder.emit_done(...) to accept optional output and error fields.
• Added/updated unit tests to cover caller-provided IDs, emit_done(output=..., error=...), and return-type behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/streaming/_event_stream.py	Adds optional item_id support for MCP call item creation with basic validation.
sdk/agentserver/azure-ai-agentserver-responses/azure/ai/agentserver/responses/streaming/_builders/_tools.py	Adds output/error support to mcp_call done emission.
sdk/agentserver/azure-ai-agentserver-responses/tests/unit/test_builders.py	Adds tests for caller-supplied MCP IDs and includes output/error in done events.
sdk/agentserver/azure-ai-agentserver-responses/tests/unit/test_emit_return_types.py	Verifies return type remains ResponseOutputItemDoneEvent when passing output/error.

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