Python: propagate as_tool() kwargs. Add sample for runtime context with as_tool kwargs and middleware.

[moonbox3]

Motivation and Context

This was originally raised in #2251 and then addressed as part of #2290. The question revolved around being able to pass runtime context using as_tool() which currently doesn't accept kwargs. As an alternative, one could use a closure around middleware. Added a sample to show this as well.

Description

• Closes Python: How to pass runtime context (auth tokens, session data) to sub-agent tools in hierarchical delegation? #2290
• Adds unit tests for kwargs passed to as_tool()
• Add sample

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	288	51	82%	329, 388–390, 436, 490, 508, 670, 849, 852–854, 977–980, 982, 985–987, 1072, 1113, 1115, 1124–1129, 1135, 1137, 1147–1148, 1155, 1157–1158, 1166–1170, 1178–1179, 1181, 1186, 1188, 1222, 1263–1264, 1266, 1279
_tools.py	602	65	89%	225, 271, 322, 324, 487, 519–520, 620, 622, 646, 651, 653, 660, 690, 744–746, 784, 807, 809–818, 827–833, 861, 903, 912, 914, 917, 923, 1297–1301, 1401, 1470, 1571, 1577, 1618–1619, 1751, 1790–1791, 1819–1821, 1856–1857, 1920–1921, 1928–1929
observability.py	610	98	83%	238, 264–266, 268, 270–274, 282–283, 288–289, 294–299, 322–324, 326–327, 333, 417, 427, 449, 455, 474–476, 484–486, 509–511, 521–523, 656, 658, 745–749, 752–756, 765–768, 778–781, 783, 1050, 1200–1202, 1360, 1368, 1372, 1376, 1382, 1384, 1386, 1394, 1404, 1432–1433, 1446–1449, 1468–1470, 1472–1475, 1477–1478, 1482, 1485, 1543, 1559, 1563, 1697, 1699
TOTAL	15000	2207	85%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
2047	127 💤	0 ❌	0 🔥	39.775s ⏱️

[Copilot]

Pull Request Overview

This PR adds support for propagating runtime context (such as API tokens, session data, and tenant IDs) through the as_tool() delegation mechanism. Previously, as_tool() did not support passing kwargs to sub-agents, requiring users to rely on alternative patterns like closures with middleware.

Key changes:

• Enabled kwargs propagation through as_tool() for hierarchical agent delegation
• Added filtering to prevent duplicate chat_options keyword arguments
• Added comprehensive test coverage for the new functionality

Reviewed Changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
python/packages/core/agent_framework/_agents.py	Modified as_tool() to forward kwargs (except arg_name) to sub-agents; added chat_options filtering in run() and run_stream() methods
python/packages/core/agent_framework/_tools.py	Added _forward_runtime_kwargs attribute to AIFunction; updated invoke() and _auto_invoke_function() to conditionally propagate runtime kwargs
python/packages/core/agent_framework/observability.py	Added chat_options filtering in trace decorators to prevent duplicate keyword argument errors
python/packages/core/tests/core/test_as_tool_kwargs_propagation.py	Added comprehensive test suite covering kwargs forwarding, filtering, nested delegation, streaming, and isolation scenarios
python/packages/core/tests/core/test_tools.py	Added test to verify ai_function tools handle additional kwargs correctly
python/samples/getting_started/middleware/runtime_context_delegation.py	Added comprehensive sample demonstrating three patterns for runtime context delegation
python/samples/README.md	Added documentation entry for the new runtime context delegation sample
python/uv.lock	Version bump