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adk-python/contributing/samples/mcp_server_side_sampling/mcp_server.py
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George Weale 2367901ec5 chore: Upgrade to headers to 2026
Co-authored-by: George Weale <gweale@google.com>
PiperOrigin-RevId: 858763407
2026-01-20 14:50:09 -08:00

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Python

# Copyright 2026 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
import os
from fastmcp import Context
from fastmcp import FastMCP
from fastmcp.experimental.sampling.handlers.openai import OpenAISamplingHandler
from openai import OpenAI
logging.basicConfig(level=logging.INFO)
API_KEY = os.getenv("OPENAI_API_KEY")
# Set up the server's LLM handler using the OpenAI API.
# This handler will be used for all sampling requests from tools on this server.
llm_handler = OpenAISamplingHandler(
default_model="gpt-4o",
client=OpenAI(
api_key=API_KEY,
),
)
# Create the FastMCP Server instance.
# The `sampling_handler` is configured to use the server's own LLM.
# `sampling_handler_behavior="always"` ensures the server never delegates
# sampling back to the ADK agent.
mcp = FastMCP(
name="SentimentAnalysis",
sampling_handler=llm_handler,
sampling_handler_behavior="always",
)
@mcp.tool
async def analyze_sentiment(text: str, ctx: Context) -> dict:
"""Analyzes sentiment by delegating to the server's own LLM."""
logging.info("analyze_sentiment tool called with text: %s", text)
prompt = f"""Analyze the sentiment of the following text as positive,
negative, or neutral. Just output a single word.
Text to analyze: {text}"""
# This delegates the LLM call to the server's own sampling handler,
# as configured in the FastMCP instance.
logging.info("Attempting to call ctx.sample()")
try:
response = await ctx.sample(prompt)
logging.info("ctx.sample() successful. Response: %s", response)
except Exception as e:
logging.error("ctx.sample() failed: %s", e, exc_info=True)
raise
sentiment = response.text.strip().lower()
if "positive" in sentiment:
result = "positive"
elif "negative" in sentiment:
result = "negative"
else:
result = "neutral"
logging.info("Sentiment analysis result: %s", result)
return {"text": text, "sentiment": result}
if __name__ == "__main__":
print("Starting FastMCP server with tool 'analyze_sentiment'...")
# This runs the server process, which the ADK agent will connect to.
mcp.run()