Python: Propagate conversation_id in Agent-as-Tool scenarios

[giles17]

Motivation and Context

When using the Agent-as-Tool pattern (a coordinator agent invoking sub-agents as tools), the parent agent's conversation_id is not propagated to sub-agents. This makes it impossible to correlate the full multi-agent interaction chain using a single identifier for persistence or observability.

Solution

Leverage the existing **kwargs forwarding pipeline (additional_function_arguments → _auto_invoke_function → tool **kwargs) to propagate conversation_id from parent to child agents.

Closes #3411

Description

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

[markwallace-microsoft]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/core/agent_framework
_agents.py	330	35	89%	474, 905, 942, 1042–1044, 1157, 1198, 1200, 1209–1214, 1220, 1222, 1232–1233, 1240, 1242–1243, 1251–1255, 1263–1264, 1266, 1271, 1273, 1307, 1347, 1367
_mcp.py	406	64	84%	104–105, 115–120, 131, 136, 182–183, 193–198, 208–209, 261, 270, 333, 341, 362, 476, 543, 578, 580, 584–585, 587–588, 642, 657, 675, 716, 822, 835–840, 862, 899–900, 906–908, 927, 952–953, 957–961, 978–982, 1126
_tools.py	757	84	88%	175–176, 306, 308, 326–328, 335, 353, 367, 379, 384, 386, 393, 430, 453–455, 504–506, 569, 591, 615–641, 676, 684, 925, 1187, 1244, 1248, 1327–1331, 1349, 1351–1352, 1464, 1468, 1518, 1520, 1536, 1538, 1602, 1629, 1686, 1754, 1933–1934, 1962, 1970, 1983, 1993–1994, 2029, 2086, 2118
packages/core/agent_framework/azure
_responses_client.py	51	6	88%	189, 221, 287–290
TOTAL	21270	3276	84%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
4107	225 💤	0 ❌	0 🔥	1m 9s ⏱️

[Copilot]

Pull request overview

This PR implements conversation ID propagation in Agent-as-Tool scenarios to enable correlation of multi-agent interactions. When a parent agent invokes a sub-agent as a tool, the parent's conversation_id is now automatically forwarded to the sub-agent via additional_function_arguments with the key parent_conversation_id. This solves issue #3411 where multi-agent conversations couldn't be correlated using a single identifier.

Changes:

• Modified as_tool() wrapper to extract parent's conversation_id and pass it to sub-agents via additional_function_arguments
• Updated _auto_invoke_function to forward conversation_id to tools instead of filtering it out
• Added logic to populate additional_function_arguments["conversation_id"] when chat API returns a conversation ID
• Added comprehensive test coverage for the new functionality
• Included a well-documented sample demonstrating the feature

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
python/packages/core/agent_framework/_agents.py	Modified as_tool() wrapper to propagate parent's conversation_id to sub-agent via additional_function_arguments with key parent_conversation_id
python/packages/core/agent_framework/_tools.py	Removed conversation_id from filter list in _auto_invoke_function to allow forwarding; added conversation_id to additional_function_arguments when received from chat API
python/packages/core/tests/core/test_as_tool_kwargs_propagation.py	Added tests for conversation_id propagation via options and handling when absent
python/packages/core/tests/core/test_agents.py	Added tests for conversation_id propagation in agent-as-tool scenarios
python/packages/core/tests/core/test_tools.py	Added tests for conversation_id forwarding and internal kwargs filtering
python/samples/getting_started/tools/agent_as_tool_conversation_id_propagation.py	New comprehensive sample demonstrating conversation_id propagation with observability middleware
python/samples/getting_started/tools/README.md	Added entry documenting the new sample
python/packages/core/agent_framework/_mcp.py	Code formatting improvements (multi-line json.dumps calls)
python/packages/core/agent_framework/azure/_responses_client.py	Code formatting improvements (line breaking)
python/packages/core/tests/core/test_mcp.py	Alphabetical import reordering