langchain

Metorial + LangChain

Uses LangChain with Anthropic Claude and LangGraph to run a ReAct agent with MCP tool calls via Metorial. The example uses Metorial Search (built-in web search) by default — no dashboard setup needed.

Environment variables

• METORIAL_API_KEY — get one at platform.metorial.com
• ANTHROPIC_API_KEY — from console.anthropic.com

Run

cp .env.example .env
pip install -r requirements.txt
python example.py

How it works

This README snippet uses bare await for readability. For a runnable script, see example.py.

import os

from langchain_anthropic import ChatAnthropic
from langgraph.prebuilt import create_react_agent

# Initialize the Metorial client
from metorial import Metorial, metorial_langchain

metorial = Metorial(api_key=os.getenv("METORIAL_API_KEY"))

# Create a deployment for Metorial Search
deployment = metorial.provider_deployments.create(
    name="Metorial Search",
    provider_id="metorial-search",
)

# Connect and resolve LangChain tools directly
session = await metorial.connect(
    adapter=metorial_langchain(),
    providers=[
        {"provider_deployment_id": deployment.id},
    ],
)

# Pass tools to a LangGraph ReAct agent, which handles the tool call
# loop automatically
llm = ChatAnthropic(model="claude-sonnet-4-20250514")
agent = create_react_agent(llm, session.tools())

# The ReAct agent will call tools as needed — making search queries,
# reading results, and synthesizing a final answer
result = await agent.ainvoke(
    {"messages": [("user", "Search the web for the latest news about AI agents and summarize the top 3 stories.")]}
)
print(result["messages"][-1].content)

Adding OAuth providers

To add a provider that requires OAuth (like Slack or GitHub), uncomment the second entry in the providers list and provide your deployment and auth config IDs. See the main README for details on setting up OAuth.