MCP Server Framework and Tool Development library for building custom capabilities into agents.
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Eric Gustin 5602578b2f
Worker Stability (#688)
This PR does three things:
1. Executes synchronous tool calls in thread pool allowing for up to 4 +
# of CPUs executions in parallel.
2. Makes force quitting via double SIGINT/SIGTERM possible and via
single SIGINT/SIGTERM + graceful shutdown timeout expiry possible, even
if there are active connections.
3. Sets `timeout_graceful_shutdown` to
`ARCADE_UVICORN_TIMEOUT_GRACEFUL_SHUTDOWN` env var if set, else defaults
to 15.
4. Disable the worker health check span to reduce noise

Tradeoffs:
Since this PR introduces executing synchronous tools via `await
asyncio.to_thread(func, **func_args)`, this means that there is no way
for the thread to be killed until it finishes. The ramifications of this
is that the force quitting logic that is also implemented in this PR has
to be very harsh `os._exit(1)` just in case there is a sync tool
actively executing. This means that `MCPApp` teardown logic will not
execute when force quitting is required. Although this was already the
case because we weren't previously able to force quit! This tradeoff is
justified for now since "parallel" tool executions will relieve us of
many worker timeouts that we are seeing in prod.

Future work:
Minimize/eliminate the need for `os._exit(1)` such that `MCPApp`
teardown logic will always execute, even when force quitting. The
solution will likely be moving away from `await asyncio.to_thread(func,
**func_args)` (while maintaining "parallelism" and then utilize the
`TaskTrackerMiddleware` introduced in this PR to cancel all of the
active HTTP requests.

Resolves PLT-713
2025-11-20 11:13:41 -08:00
.github Update release-on-version-change.yml (#671) 2025-11-03 11:55:56 -08:00
.vscode Rename some 'toolkit' references to 'server' (#624) 2025-10-14 18:42:27 -07:00
contrib General OSS health (#643) 2025-10-22 18:26:27 -07:00
docker HubSpot Automation & CMS Starter tools (#669) 2025-10-31 20:13:18 -03:00
examples Rename example servers (#675) 2025-11-12 10:21:25 -08:00
libs Worker Stability (#688) 2025-11-20 11:13:41 -08:00
schemas/preview Tool Metadata (#357) 2025-04-16 19:17:36 -08:00
toolkits Remove arcade engine api - moving to starter-tools repo (#686) 2025-11-11 15:49:38 -08:00
.editorconfig Fix ruff (#64) 2024-09-25 09:47:30 -07:00
.gitignore Re-import arcade_core errors into arcade_mcp_server (#620) 2025-10-13 17:48:54 -07:00
.pre-commit-config.yaml MCP Local (#563) 2025-09-25 15:28:15 -07:00
.prettierignore Fix ruff (#64) 2024-09-25 09:47:30 -07:00
.prettierrc.toml Fix ruff (#64) 2024-09-25 09:47:30 -07:00
.ruff.toml MCP Local (#563) 2025-09-25 15:28:15 -07:00
CONTRIBUTING.md Rename some 'toolkit' references to 'server' (#624) 2025-10-14 18:42:27 -07:00
cspell.config.yaml Replace arcade.client with arcadepy (#119) 2024-10-23 15:29:02 -07:00
LICENSE Update README and LICENSE (#220) 2025-01-23 19:43:48 -08:00
Makefile Rename _meta requirements field to arcade_requirements (#616) 2025-10-14 19:01:05 -07:00
pyproject.toml Worker Stability (#688) 2025-11-20 11:13:41 -08:00
README.md Fix MCP capabilities, examples, tests, and more (#657) 2025-10-30 11:59:00 -07:00
uv_setup.sh MCP Local (#563) 2025-09-25 15:28:15 -07:00

Prebuilt ToolsContact Us

Arcade MCP Server Framework

  • To see example servers built with Arcade MCP Server Framework (this repo), check out our examples

  • To learn more about the Arcade MCP Server Framework (this repo), check out our Arcade MCP documentation

  • To learn more about other offerings from Arcade.dev, check out our documentation.

Pst. hey, you, give us a star if you like it!

GitHub stars

Quick Start: Create a New Server

The fastest way to get started is with the arcade new CLI command, which creates a complete MCP server project:

# Install the CLI
uv tool install arcade-mcp

# Create a new server project
arcade new my_server

# Navigate to the project
cd my_server/src/my_server

This generates a project with:

  • server.py - Main server file with MCPApp and example tools

  • pyproject.toml - Dependencies and project configuration

  • .env.example - Example .env file containing a secret required by one of the generated tools in server.py

The generated server.py includes proper command-line argument handling and three example tools:

#!/usr/bin/env python3
"""simple_server MCP server"""

import sys
from typing import Annotated

import httpx
from arcade_mcp_server import Context, MCPApp
from arcade_mcp_server.auth import Reddit

app = MCPApp(name="simple_server", version="1.0.0", log_level="DEBUG")


@app.tool
def greet(name: Annotated[str, "The name of the person to greet"]) -> str:
    """Greet a person by name."""
    return f"Hello, {name}!"


# To use this tool locally, you need to either set the secret in the .env file or as an environment variable
@app.tool(requires_secrets=["MY_SECRET_KEY"])
def whisper_secret(context: Context) -> Annotated[str, "The last 4 characters of the secret"]:
    """Reveal the last 4 characters of a secret"""
    # Secrets are injected into the context at runtime.
    # LLMs and MCP clients cannot see or access your secrets
    # You can define secrets in a .env file.
    try:
        secret = context.get_secret("MY_SECRET_KEY")
    except Exception as e:
        return str(e)

    return "The last 4 characters of the secret are: " + secret[-4:]

# To use this tool locally, you need to install the Arcade CLI (uv tool install arcade-mcp)
# and then run 'arcade login' to authenticate.
@app.tool(requires_auth=Reddit(scopes=["read"]))
async def get_posts_in_subreddit(
    context: Context, subreddit: Annotated[str, "The name of the subreddit"]
) -> dict:
    """Get posts from a specific subreddit"""
    # Normalize the subreddit name
    subreddit = subreddit.lower().replace("r/", "").replace(" ", "")

    # Prepare the httpx request
    # OAuth token is injected into the context at runtime.
    # LLMs and MCP clients cannot see or access your OAuth tokens.
    oauth_token = context.get_auth_token_or_empty()
    headers = {
        "Authorization": f"Bearer {oauth_token}",
        "User-Agent": "{{ toolkit_name }}-mcp-server",
    }
    params = {"limit": 5}
    url = f"https://oauth.reddit.com/r/{subreddit}/hot"

    # Make the request
    async with httpx.AsyncClient() as client:
        response = await client.get(url, headers=headers, params=params)
        response.raise_for_status()

        # Return the response
        return response.json()

# Run with specific transport
if __name__ == "__main__":
    # Get transport from command line argument, default to "stdio"
    # - "stdio" (default): Standard I/O for Claude Desktop, CLI tools, etc.
    #   Supports tools that require_auth or require_secrets out-of-the-box
    # - "http": HTTPS streaming for Cursor, VS Code, etc.
    #   Does not support tools that require_auth or require_secrets unless the server is deployed
    #   using 'arcade deploy' or added in the Arcade Developer Dashboard with 'Arcade' server type
    transport = sys.argv[1] if len(sys.argv) > 1 else "stdio"

    # Run the server
    app.run(transport=transport, host="127.0.0.1", port=8000)

This approach gives you:

  • Complete Project Setup - Everything you need in one command

  • Best Practices - Proper dependency management with pyproject.toml

  • Example Code - Learn from working examples of common patterns

  • Production Ready - Structured for growth and deployment

Running Your Server

Run your server directly with Python:

# Run with stdio transport (default)
uv run server.py

# Run with http transport via command line argument
uv run server.py http

# Or use python directly
python server.py http
python server.py stdio

Your server will start and listen for connections. With HTTP transport, you can access the API docs at http://127.0.0.1:8000/docs.

Configure MCP Clients

Once your server is running, connect it to your favorite AI assistant:

arcade configure claude # Configure Claude Desktop to connect to your stdio server in your current directory
arcade configure cursor --transport http --port 8080 # Configure Cursor to connect to your local HTTP server on port 8080
arcade configure vscode --entrypoint my_server.py # Configure VSCode to connect to your stdio server that will run when my_server.py is executed directly

Installing this Repo from Source

git clone https://github.com/ArcadeAI/arcade-mcp.git && cd arcade-mcp && make install

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