Python: [Bug]: "Duplicate item found" error when using AzureAIClient with tools in workflows

[firrasaltaher]

Description

Summary

When using AzureAIClient with agents that have tools in a workflow, the Azure AI API returns a 400 error: "Duplicate item found with id fc_xxxxx. Remove duplicate items from your input and try again." This prevents workflows with tool-enabled agents from executing.

Environment

• agent-framework version: 1.0.0b260116
• agent-framework-azure-ai version: 1.0.0b260116
• agent-framework-core version: 1.0.0b260116
• Python version: 3.12.11
• OS: Windows 11
• Azure AI API version: 2025-11-15-preview
• Date: January 19, 2026

Steps to Reproduce

1. Create a workflow with multiple agents using AzureAIClient
2. Configure at least one agent with tools using the tools= parameter in as_agent()
3. Run the workflow with workflow.run_stream(query)
4. Observe the error when the agent with tools attempts to execute

Minimal Reproduction Code

import asyncio
import os
from dotenv import load_dotenv
from azure.ai.projects.aio import AIProjectClient
from azure.identity.aio import DefaultAzureCredential
from agent_framework import ai_function, WorkflowBuilder, executor, WorkflowContext, ChatMessage
from agent_framework.azure import AzureAIClient

load_dotenv()

# Define a simple tool
@ai_function(name="search_hotels", description="Search for hotels")
def search_hotels(location: str) -> str:
    return f"Mock hotel results for {location}"

@executor(id="start")
async def start_executor(input: str, ctx: WorkflowContext[str, str]) -> None:
    await ctx.send_message([ChatMessage(role="user", text=input)])

async def main():
    project_client = AIProjectClient(
        endpoint=os.environ["AZURE_AI_PROJECT_ENDPOINT"],
        credential=DefaultAzureCredential(),
        api_version="2025-11-15-preview",
    )

    async with (
        DefaultAzureCredential() as credential,
        project_client,
        AzureAIClient(project_client=project_client, credential=credential) as client,
    ):
        # Create agent with tools
        hotel_search_client = AzureAIClient(
            project_client=project_client, 
            credential=credential, 
            agent_name="hotel-agent"
        )
        hotel_agent = hotel_search_client.as_agent(
            id="hotel-agent",
            instructions="Search for hotels using the search_hotels tool.",
            name="hotel-agent",
            tools=[search_hotels],  # ← This causes the bug
            store=True,
        )

        # Build simple workflow
        workflow = (
            WorkflowBuilder()
            .set_start_executor(start_executor)
            .add_edge(start_executor, hotel_agent)
            .build()
        )

        # Run workflow - this will fail
        async for event in workflow.run_stream("Find hotels in Paris"):
            print(event)

if __name__ == "__main__":
    asyncio.run(main())

Expected Behavior

The workflow should execute successfully, with the agent calling the search_hotels tool and returning results based on the tool output.

Actual Behavior

The workflow fails with the following error:

Error during workflow execution: <class 'agent_framework_azure_ai._client.AzureAIClient'> service failed to complete the prompt: Error code: 400 - {'error': {'message': 'Duplicate item found with id fc_047d0ef380cbbb9f00696f01af725881959ee4e2494b72def8. Remove duplicate items from your input and try again.', 'type': 'invalid_request_error', 'param': 'input', 'code': None}}

Traceback (most recent call last):
  File "agent_framework\openai\_responses_client.py", line 266, in _inner_get_streaming_response
    async for chunk in await client.responses.create(stream=True, **run_options):
  ...
openai.BadRequestError: Error code: 400 - {'error': {'message': 'Duplicate item found with id fc_047d0ef380cbbb9f00696f01af725881959ee4e2494b72def8. Remove duplicate items from your input and try again.', 'type': 'invalid_request_error', 'param': 'input', 'code': None}}

The error indicates that function call items with the same ID are being duplicated in the API request payload, which the Azure AI Responses API rejects.

Code Sample

Run the sample: https://github.com/microsoft/agent-framework/tree/main/python/samples/demos/workflow_evaluation

or

### Minimal Reproduction Code


import asyncio
import os
from dotenv import load_dotenv
from azure.ai.projects.aio import AIProjectClient
from azure.identity.aio import DefaultAzureCredential
from agent_framework import ai_function, WorkflowBuilder, executor, WorkflowContext, ChatMessage
from agent_framework.azure import AzureAIClient

load_dotenv()

# Define a simple tool
@ai_function(name="search_hotels", description="Search for hotels")
def search_hotels(location: str) -> str:
    return f"Mock hotel results for {location}"

@executor(id="start")
async def start_executor(input: str, ctx: WorkflowContext[str, str]) -> None:
    await ctx.send_message([ChatMessage(role="user", text=input)])

async def main():
    project_client = AIProjectClient(
        endpoint=os.environ["AZURE_AI_PROJECT_ENDPOINT"],
        credential=DefaultAzureCredential(),
        api_version="2025-11-15-preview",
    )

    async with (
        DefaultAzureCredential() as credential,
        project_client,
        AzureAIClient(project_client=project_client, credential=credential) as client,
    ):
        # Create agent with tools
        hotel_search_client = AzureAIClient(
            project_client=project_client, 
            credential=credential, 
            agent_name="hotel-agent"
        )
        hotel_agent = hotel_search_client.as_agent(
            id="hotel-agent",
            instructions="Search for hotels using the search_hotels tool.",
            name="hotel-agent",
            tools=[search_hotels],  # ← This causes the bug
            store=True,
        )

        # Build simple workflow
        workflow = (
            WorkflowBuilder()
            .set_start_executor(start_executor)
            .add_edge(start_executor, hotel_agent)
            .build()
        )

        # Run workflow - this will fail
        async for event in workflow.run_stream("Find hotels in Paris"):
            print(event)

if __name__ == "__main__":
    asyncio.run(main())

Error Messages / Stack Traces

The workflow fails with the following error:


Error during workflow execution: <class 'agent_framework_azure_ai._client.AzureAIClient'> service failed to complete the prompt: Error code: 400 - {'error': {'message': 'Duplicate item found with id fc_047d0ef380cbbb9f00696f01af725881959ee4e2494b72def8. Remove duplicate items from your input and try again.', 'type': 'invalid_request_error', 'param': 'input', 'code': None}}

Traceback (most recent call last):
  File "agent_framework\openai\_responses_client.py", line 266, in _inner_get_streaming_response
    async for chunk in await client.responses.create(stream=True, **run_options):
  ...
openai.BadRequestError: Error code: 400 - {'error': {'message': 'Duplicate item found with id fc_047d0ef380cbbb9f00696f01af725881959ee4e2494b72def8. Remove duplicate items from your input and try again.', 'type': 'invalid_request_error', 'param': 'input', 'code': None}}


The error indicates that function call items with the same ID are being duplicated in the API request payload, which the Azure AI Responses API rejects.

Package Versions

agent-framework version: 1.0.0b260116, agent-framework-azure-ai version: 1.0.0b260116, agent-framework-core version: 1.0.0b260116

Python Version

No response

Additional Context

What Works

• ✅ Workflows with AzureAIClient agents WITHOUT tools work perfectly
• ✅ Single agents (non-workflow) with AzureAIClient and tools work
• ✅ The official sample at python/samples/demos/workflow_evaluation/ has the same structure but appears to have the same issue

What Doesn't Work

• ❌ Multi-agent workflows with AzureAIClient where agents have the tools= parameter
• ❌ Both fan-out and sequential workflow patterns exhibit this issue
• ❌ Error occurs consistently across different tool configurations

Workaround

Remove the tools= parameter from agents in workflows and have them use their knowledge instead:

# Instead of:
hotel_agent = client.as_agent(
    id="hotel-agent",
    instructions="Use search_hotels to find hotels.",
    tools=[search_hotels],  # ← Remove this
    store=True,
)

# Use:
hotel_agent = client.as_agent(
    id="hotel-agent",
    instructions="Based on the request, suggest hotels using your knowledge.",
    # No tools parameter
    store=True,
)

Related Code References

• Official sample with same pattern: python/samples/demos/workflow_evaluation/create_workflow.py
• Error occurs in: agent_framework/openai/_responses_client.py, line 266
• Related to Azure AI Responses API tool handling in workflow contexts

Suspected Root Cause

The agent framework appears to be sending duplicate function call items in the request payload when:

1. Multiple agents in a workflow have tools
2. The workflow uses fan-out or sequential patterns
3. Message history is being passed between agents

This could be related to how tool definitions or function call tracking is handled across workflow agent boundaries in the AzureAIClient implementation.

Impact

• Severity: High - Blocks using tools in multi-agent workflows with AzureAIClient
• Scope: Affects Azure AI Foundry integration (AzureAIClient) specifically
• Frequency: 100% reproduction rate when tools are used in workflows

Suggested Fix Areas

1. Review how AzureAIClient constructs the Responses API payload for agents with tools
2. Check for duplicate function call ID tracking across workflow agent invocations
3. Verify message history sanitization when passing between workflow agents
4. Ensure tool definitions aren't being registered multiple times per workflow execution

Additional Files

• Full reproduction case: create_workflow.py (with tools - fails)
• Working workaround: create_workflow_no_tools.py (without tools - succeeds)
• Tool definitions: _tools.py