Python: multiple bug fixes

[eavanvalkenburg]

Motivation and Context

Fixes #3147 by overriding error message for AzureAIClient.
Fixes #3118 by adding kwargs in the same way for run as we do in run_stream
Fixes #3041 by completely serializing the function result in the span attribute

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/azure-ai/agent_framework_azure_ai
_client.py	193	43	77%	221–224, 229, 232–235, 240, 243–244, 247, 254, 293, 295–298, 300, 408, 426–429, 472, 508–511, 516, 518–519, 521–529, 531
packages/core/agent_framework
_agents.py	291	52	82%	329, 390–392, 438, 492, 510, 672, 853, 856–858, 994–997, 999, 1002–1004, 1100, 1141, 1143, 1152–1157, 1163, 1165, 1175–1176, 1183, 1185–1186, 1194–1198, 1206–1207, 1209, 1214, 1216, 1250, 1295–1296, 1298, 1300, 1311
_tools.py	728	69	90%	226, 272, 323, 325, 353, 523, 555–556, 658, 660, 680, 698, 712, 724, 729, 731, 738, 771, 827–829, 870, 893, 895–904, 913–919, 955, 965, 1149, 1485, 1563–1567, 1688, 1757, 1850, 1856, 1899–1900, 1913–1914, 2043, 2084–2085, 2113–2115, 2157–2158, 2223–2224, 2231–2232
packages/core/agent_framework/azure
_responses_client.py	36	6	83%	106, 129, 156–159
packages/core/agent_framework/openai
_responses_client.py	513	100	80%	141, 144, 146–147, 156, 174, 182, 185–192, 194, 199, 205, 209, 224, 227–228, 230, 267, 297, 341–342, 364, 369, 418, 421, 457, 470, 521, 597, 602, 606–608, 628, 643–644, 648–650, 697, 717–718, 731–732, 748–749, 827–828, 837–838, 869–870, 886, 888, 962–970, 993–999, 1018, 1033–1034, 1043, 1048–1050, 1056–1057, 1070, 1082, 1113–1114, 1116–1118, 1129–1130, 1133, 1135, 1145–1146, 1152, 1167
TOTAL	17640	2894	83%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
2617	154 💤	0 ❌	0 🔥	59.326s ⏱️

[Copilot]

Pull request overview

This pull request fixes three bugs in the Python agent framework:

• Fixes #3147 by allowing AzureAIClient to provide a custom error message when model_deployment_name is missing
• Fixes #3118 by ensuring kwargs are properly forwarded in the Agent.run() method, consistent with run_stream()
• Fixes #3041 by using the prepare_function_call_results() function for better serialization of function results in span attributes

Key Changes

• Extracted model presence validation into a separate overridable method _check_model_presence()
• Changed function result serialization in observability spans to use prepare_function_call_results() instead of json.dumps()
• Added **kwargs forwarding to _prepare_thread_and_messages() call in Agent.run()

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
python/packages/core/agent_framework/openai/_responses_client.py	Refactored model_id validation into separate _check_model_presence() method to enable subclass customization
python/packages/core/agent_framework/_tools.py	Updated function result serialization to use prepare_function_call_results() for better handling of complex types
python/packages/core/agent_framework/_agents.py	Added **kwargs forwarding in run() method to match run_stream() behavior
python/packages/azure-ai/agent_framework_azure_ai/_client.py	Overrode _check_model_presence() to provide Azure-specific error message referencing model_deployment_name