Python: Add incomplete details reason to AzureAIAgent error message (#12796)

### Motivation and Context

When errors occur processing a run of an AzureAIAgent, we surface the
error message but not the incomplete_details reason if it exists.

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### Description

This PR adds handling for the incomplete details reason, if it exists,
so it can be passed back via the error message.
- Closes #12752

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### Contribution Checklist

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- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

Author: moonbox3

python/samples/getting_started_with_agents/openai_responses/README.md

@@ -15,12 +15,7 @@ In Semantic Kernel, we don't currently support the Computer User Agent Tool. Thi
 The Semantic Kernel Azure Responses Agent leverages Azure OpenAI's new stateful API. 
 It brings together the best capabilities from the chat completions and assistants API in one unified experience.
 
-Right now, there is no support with the `AzureResponsesAgent` for:
-
-- Structured outputs
-- tool_choice
-- image_url pointing to an internet address
-- The web search tool is also not supported, and is not part of the 2025-03-01-preview API.
+For `AzureResponsesAgent` limitations, please see the latest [Azure OpenAI Responses API Docs](https://learn.microsoft.com/en-us/azure/ai-foundry/openai/how-to/responses?tabs=python-secure).
 
 #### API Support
 

python/semantic_kernel/agents/azure_ai/agent_thread_actions.py

@@ -199,12 +199,15 @@ async def invoke(
             )
 
             if run.status in cls.error_message_states:
-                error_message = ""
+                error_message = "None"
                 if run.last_error and run.last_error.message:
                     error_message = run.last_error.message
+                incomplete_details_reason = "None"
+                if run.incomplete_details and run.incomplete_details.reason:
+                    incomplete_details_reason = run.incomplete_details.reason
                 raise AgentInvokeException(
                     f"Run failed with status: `{run.status}` for agent `{agent.name}` and thread `{thread_id}` "
-                    f"with error: {error_message}"
+                    f"with error: {error_message} and incomplete details reason: {incomplete_details_reason}"
                 )
 
             # Check if function calling is required
@@ -738,12 +741,16 @@ async def _process_stream_events(
 
                 elif event_type == AgentStreamEvent.THREAD_RUN_FAILED:
                     run_failed = cast(ThreadRun, event_data)
-                    error_message = (
-                        run_failed.last_error.message if run_failed.last_error and run_failed.last_error.message else ""
-                    )
+                    error_message = "None"
+                    if run_failed.last_error and run_failed.last_error.message:
+                        error_message = run_failed.last_error.message
+                    incomplete_details_reason = "None"
+                    if run_failed.incomplete_details and run_failed.incomplete_details.reason:
+                        incomplete_details_reason = run_failed.incomplete_details.reason
                     raise RuntimeError(
                         f"Run failed with status: `{run_failed.status}` for agent `{agent.name}` "
-                        f"thread `{thread_id}` with error: {error_message}"
+                        f"thread `{thread_id}` with error: {error_message} and incomplete details reason: "
+                        f"{incomplete_details_reason}"
                     )
             else:
                 break