CrewAI

pip install crewai mcp

CrewAI runs on Python 3.10 to 3.13. Its agents call OpenAI unless you give them another model, so set OPENAI_API_KEY or pass llm.

npx @nextmail/cli login

Choose the browser sign-in. On the approval page, pick the workspace, the access, the addresses the crew may reach and how long the approval lasts. Read only is the default, and it leaves out tools such as sendEmail, replyToEmail and createDraft, so choose Read and send when the agent should draft or reply. The sign-in is saved on this machine and listed in Account → Command line, where you can narrow it or remove it. A sign-in the bridge has not used for 7 days, or one whose approval has ended, has to sign in again.

On a server or over SSH, add --no-browser: open the link on any device, approve, and paste the code it shows back into the terminal. A browser sign-in needs a person once, so a CI job cannot make one.

from crewai import Agent, Crew, Taskfrom crewai.mcp import MCPServerStdiofrom crewai.mcp.filters import create_static_tool_filter mailbox = MCPServerStdio(    command="npx",    args=["-y", "@nextmail/cli", "mcp", "serve"],    tool_filter=create_static_tool_filter(        allowed_tool_names=["whoAmI", "listThreads", "getThread"]    ),) reader = Agent(    role="Inbox reader",    goal="Know what is waiting in the inbox",    backstory="You read mail carefully and never send anything.",    mcps=[mailbox],) summary = Task(    description="Summarise my unread mail.",    expected_output="One line per conversation: who wrote, what they want, and whether it needs a reply.",    agent=reader,) print(Crew(agents=[reader], tasks=[summary]).kickoff())

The framework starts the local bridge, npx -y @nextmail/cli mcp serve, as a stdio MCP server. The bridge sends each call to the MCP server with your saved sign-in and renews the access token when it runs out, so the agent never handles a token. To use another profile of the command line, add --profile <name> to the arguments. The bridge runs on Node.js 20.12 or later.

• —mcps on an agent takes MCPServerStdio, which starts the bridge and loads its tools for that agent.
• —create_static_tool_filter matches the names the server lists. CrewAI then puts the server name in front of each tool it hands the agent.

The server registers up to 600 tools, and the crew sees the ones both your role and the approval allow. A tool the approval leaves out is never listed, so the model never tries it. Every tool loaded is sent to the model on each turn, so give the agent the ones its job needs. The example starts from whoAmI, listThreads and getThread.

The MCP support in CrewAI’s open-source library sends static headers and runs no OAuth sign-in. An access token pasted into headers stops working within the hour, while the bridge renews its token by itself, so a crew connects through the bridge.