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# mypy: ignore-errors
"""Custom MCP simple sample.
This sample combines the patterns from:
- langgraph `mcp_simple` (uses MultiServerMCPClient to discover tools)
- `custom_mock_agent_test` (implements a custom FoundryCBAgent with streaming events)
Goal: When invoked in stream mode, emit MCP list tools related stream events so a
consumer (UI / CLI) can visualize tool enumeration plus a final assistant
message. In non-stream mode, return a single aggregated response summarizing
the tools.
Run:
python mcp_simple.py
Then call (example):
curl -X POST http://localhost:8088/responses -H 'Content-Type: application/json' -d '{
"agent": {"name": "custom_mcp", "type": "agent_reference"},
"stream": true,
"input": "List the tools available"
}'
"""
import datetime
import json
from typing import AsyncGenerator, List
from langchain_mcp_adapters.client import MultiServerMCPClient
from azure.ai.agentserver.core import AgentRunContext, FoundryCBAgent
from azure.ai.agentserver.core.models import Response as OpenAIResponse
from azure.ai.agentserver.core.models.projects import (
ItemContentOutputText,
MCPListToolsItemResource,
MCPListToolsTool,
ResponseCompletedEvent,
ResponseCreatedEvent,
ResponseMCPListToolsCompletedEvent,
ResponseMCPListToolsInProgressEvent,
ResponseOutputItemAddedEvent,
ResponsesAssistantMessageItemResource,
ResponseTextDeltaEvent,
ResponseTextDoneEvent,
)
class MCPToolsAgent(FoundryCBAgent):
def __init__(self): # noqa: D401
super().__init__()
# Lazy init; created on first request to avoid startup latency if unused
self._mcp_client = None
async def _get_client(self) -> MultiServerMCPClient:
if self._mcp_client is None:
# Mirror langgraph sample server config
self._mcp_client = MultiServerMCPClient(
{
"mslearn": {
"url": "https://learn.microsoft.com/api/mcp",
"transport": "streamable_http",
}
}
)
return self._mcp_client
async def _list_tools(self) -> List[MCPListToolsTool]:
client = await self._get_client()
try:
raw_tools = await client.get_tools()
tools: List[MCPListToolsTool] = []
for t in raw_tools:
# Support either dict-like or attribute-based tool objects
if isinstance(t, dict):
name = t.get("name", "unknown_tool")
description = t.get("description")
schema = (
t.get("input_schema")
or t.get("schema")
or t.get("parameters")
or {}
)
else: # Fallback to attribute access
name = getattr(t, "name", "unknown_tool")
description = getattr(t, "description", None)
schema = (
getattr(t, "input_schema", None)
or getattr(t, "schema", None)
or getattr(t, "parameters", None)
or {}
)
tools.append(
MCPListToolsTool(
name=name,
description=description,
input_schema=schema,
)
)
if not tools:
raise ValueError("No tools discovered from MCP server")
return tools
except Exception: # noqa: BLE001
# Provide deterministic fallback so sample always works offline
return [
MCPListToolsTool(
name="fallback_echo",
description="Echo back provided text.",
input_schema={
"type": "object",
"properties": {"text": {"type": "string"}},
"required": ["text"],
},
)
]
async def agent_run(self, context: AgentRunContext): # noqa: D401
"""Implements the FoundryCBAgent contract.
Streaming path emits MCP list tools events + assistant summary.
Non-stream path returns aggregated assistant message.
"""
tools = await self._list_tools()
if context.stream:
async def stream() -> AsyncGenerator: # noqa: D401
# Initial empty response context (pattern from mock sample)
yield ResponseCreatedEvent(response=OpenAIResponse(output=[]))
# Indicate listing in progress
yield ResponseMCPListToolsInProgressEvent()
mcp_item = MCPListToolsItemResource(
id=context.id_generator.generate("mcp_list"),
server_label="mslearn",
tools=tools,
)
yield ResponseOutputItemAddedEvent(output_index=0, item=mcp_item)
yield ResponseMCPListToolsCompletedEvent()
# Assistant streaming summary
assistant_item = ResponsesAssistantMessageItemResource(
id=context.id_generator.generate_message_id(),
status="in_progress",
content=[ItemContentOutputText(text="", annotations=[])],
)
yield ResponseOutputItemAddedEvent(output_index=1, item=assistant_item)
summary_text = "Discovered MCP tools: " + ", ".join(
t.name for t in tools
)
assembled = ""
parts = summary_text.split(" ")
for i, token in enumerate(parts):
piece = token if i == len(parts) - 1 else token + " " # keep spaces
assembled += piece
yield ResponseTextDeltaEvent(
output_index=1, content_index=0, delta=piece
)
yield ResponseTextDoneEvent(
output_index=1, content_index=0, text=assembled
)
final_response = OpenAIResponse(
metadata={},
temperature=0.0,
top_p=0.0,
user="user",
id=context.response_id,
created_at=datetime.datetime.now(),
output=[
mcp_item,
ResponsesAssistantMessageItemResource(
id=assistant_item.id,
status="completed",
content=[
ItemContentOutputText(text=assembled, annotations=[])
],
),
],
)
yield ResponseCompletedEvent(response=final_response)
return stream()
# Non-stream path: single assistant message
# Build a JSON-serializable summary. Avoid dumping complex model/schema objects that
# can include non-serializable metaclass references (seen in error stacktrace).
safe_tools = []
for t in tools:
schema = t.input_schema
# Simplify schema to plain dict/str; if not directly serializable, fallback to string.
if isinstance(schema, (str, int, float, bool)) or schema is None:
safe_schema = schema
elif isinstance(schema, dict):
# Shallow copy ensuring nested values are primitive or stringified
safe_schema = {}
for k, v in schema.items():
if isinstance(v, (str, int, float, bool, type(None), list, dict)):
safe_schema[k] = v
else:
safe_schema[k] = str(v)
else:
safe_schema = str(schema)
safe_tools.append(
{
"name": t.name,
"description": t.description,
# Provide only top-level schema keys if dict.
"input_schema_keys": list(safe_schema.keys())
if isinstance(safe_schema, dict)
else safe_schema,
}
)
summary = {
"server_label": "mslearn",
"tool_count": len(tools),
"tools": safe_tools,
}
content = [
ItemContentOutputText(
text="MCP tool listing completed.\n" + json.dumps(summary, indent=2),
annotations=[],
)
]
return OpenAIResponse(
metadata={},
temperature=0.0,
top_p=0.0,
user="user",
id="id",
created_at=datetime.datetime.now(),
output=[
ResponsesAssistantMessageItemResource(
id=context.id_generator.generate_message_id(),
status="completed",
content=content,
)
],
)
my_agent = MCPToolsAgent()
if __name__ == "__main__":
my_agent.run()
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