Fastn Server

What is Fastn Server about?

Fastn Server enables developers to register tools dynamically and execute them based on API definitions. It acts as a unified backend that connects to external services like Slack, Notion, HubSpot, Claude.ai, and Cursor.ai, handling authentication, logging, and error management.

How to use Fastn Server?

1. Install – Preferred method is the pip package:

   pip install fastn-mcp-server
   

   Alternatively, clone the repository and install with UV in a virtual environment.
2. Configure authentication – Choose either API‑key authentication or tenant‑based authentication and provide the required flags (--api_key, --space_id, --tenant_id, --auth_token).
3. Run the server:

   fastn-mcp-server --api_key YOUR_API_KEY --space_id YOUR_WORKSPACE_ID
   

   or for tenant auth:

   fastn-mcp-server --space_id YOUR_WORKSPACE_ID --tenant_id YOUR_TENANT_ID --auth_token YOUR_AUTH_TOKEN
   

4. Integrate with AI assistants – Add the server command to Claude or Cursor configuration files as described in the README.

Key Features of Fastn Server

• Integrated platform support for services like Slack, Notion, HubSpot, Claude.ai, Cursor.ai
• Flexible authentication: API key or tenant‑based
• Comprehensive logging for troubleshooting
• Robust error handling across scenarios
• Simple CLI entry point (fastn-mcp-server)
• Compatible with Python 3.10+ and installable via pip or UV

Use Cases of Fastn Server

• Tool orchestration – Dynamically expose internal utilities as API‑driven tools for AI assistants.
• Cross‑service automation – Connect workflows across SaaS platforms (e.g., posting messages to Slack after a Notion update).
• Enterprise AI integration – Provide secure, tenant‑scoped access to internal data when using Claude or Cursor.
• Rapid prototyping – Spin up a local server to test new tool definitions without writing extensive boilerplate.

FAQ

Q: Which Python version is required? A: Python 3.10 or higher.

Q: Can I run the server without installing the pip package? A: Yes, clone the repo, set up a virtual environment with UV, and run uv run fastn-server.py with the appropriate flags.

Q: How do I expose the server to Claude.ai? A: Add a JSON entry under mcpServers in Claude's configuration file that points to the fastn-mcp-server executable and includes the required authentication arguments.

Q: What if I encounter a "Package Structure Error" during installation? A: Ensure pyproject.toml contains:

[tool.hatch.build.targets.wheel]
packages = ["."]

Then reinstall dependencies with uv pip install "httpx>=0.28.1" "mcp[cli]>=1.2.0".

Fastn Server

The Fastn server is a powerful, scalable platform that enables dynamic tool registration and execution based on API definitions. It seamlessly integrates with services like Claude.ai and Cursor.ai, providing a unified server solution for a wide range of tasks.

Features

• Integrated platform support - Use services like Slack, Notion, HubSpot, and more through the Fastn server
• Flexible authentication - Use either API key or tenant-based authentication
• Comprehensive logging - Detailed logs for troubleshooting
• Error handling - Robust error management for various scenarios

Prerequisites

• Python 3.10 or higher

Installation Options

Option 1: Package Installation (Recommended)

The easiest way to install the Fastn server is using pip:

pip install fastn-mcp-server

To find the exact path of the installed command:

• On macOS/Linux: which fastn-mcp-server
• On Windows: where fastn-mcp-server

Option 2: Manual Setup

# Clone repository and navigate to directory
git clone <your-repo-url> && cd fastn-server

# macOS/Linux: Install UV, create virtual environment, and install dependencies
curl -LsSf https://astral.sh/uv/install.sh | sh && uv venv && source .venv/bin/activate && uv pip install -e .

# Windows (PowerShell): Install UV, create a virtual environment, and install dependencies
powershell -c "irm https://astral.sh/uv/install.ps1 | iex" && uv venv && .venv\Scripts\activate && uv pip install -e .

# Install dependencies directly
uv pip install "httpx>=0.28.1" "mcp[cli]>=1.2.0"

Fastn Account Setup

1. Login to your Fastn account
2. Go to "Connectors" from the left sidebar
3. Activate the service(s) you want to use
4. Go to "Settings" from the left sidebar
5. Click on "Generate API Key" and save it (if using API Key auth)
6. Copy your Workspace ID from the top bar

Running the Server

The server supports two authentication methods:

Authentication Method 1: API Key

# Package installation
fastn-mcp-server --api_key YOUR_API_KEY --space_id YOUR_WORKSPACE_ID

# Manual installation
uv run fastn-server.py --api_key YOUR_API_KEY --space_id YOUR_WORKSPACE_ID

Authentication Method 2: Tenant-based

# Package installation
fastn-mcp-server --space_id YOUR_WORKSPACE_ID --tenant_id YOUR_TENANT_ID --auth_token YOUR_AUTH_TOKEN

# Manual installation
uv run fastn-server.py --space_id YOUR_WORKSPACE_ID --tenant_id YOUR_TENANT_ID --auth_token YOUR_AUTH_TOKEN

Integration with AI Assistants

Claude Integration

1. Open the Claude configuration file:

   • Windows: notepad "%APPDATA%\Claude\claude_desktop_config.json" or code "%APPDATA%\Claude\claude_desktop_config.json"
   • Mac: code ~/Library/Application\ Support/Claude/claude_desktop_config.json

2. Add the appropriate configuration:

Using Package Installation

{
    "mcpServers": {
        "fastn": {
            "command": "/path/to/fastn-mcp-server",
            "args": [
                "--api_key",
                "YOUR_API_KEY",
                "--space_id",
                "YOUR_WORKSPACE_ID"
            ]
        }
    }
}

Or with tenant authentication:

{
    "mcpServers": {
        "fastn": {
            "command": "/path/to/fastn-mcp-server",
            "args": [
                "--space_id",
                "YOUR_WORKSPACE_ID",
                "--tenant_id",
                "YOUR_TENANT_ID",
                "--auth_token",
                "YOUR_AUTH_TOKEN"
            ]
        }
    }
}

Using Manual Installation

API Key authentication:

{
    "mcpServers": {
        "fastn": {
            "command": "/path/to/your/uv",
            "args": [
                "--directory",
                "/path/to/your/fastn-server",
                "run",
                "fastn-server.py",
                "--api_key",
                "YOUR_API_KEY",
                "--space_id",
                "YOUR_WORKSPACE_ID"
            ]
        }
    }
}

Tenant authentication:

{
    "mcpServers": {
        "fastn": {
            "command": "/path/to/your/uv",
            "args": [
                "--directory",
                "/path/to/your/fastn-server",
                "run",
                "fastn-server.py",
                "--space_id",
                "YOUR_WORKSPACE_ID",
                "--tenant_id",
                "YOUR_TENANT_ID",
                "--auth_token",
                "YOUR_AUTH_TOKEN"
            ]
        }
    }
}

Cursor Integration

1. Open Cursor settings
2. Click on "MCP" in the settings menu
3. Click on "Add New"
4. Add a name for your server (e.g., "fastn")
5. Select "Command" as the type
6. Add the command based on your installation:

Using Package Installation

API Key authentication:

/path/to/fastn-mcp-server --api_key YOUR_API_KEY --space_id YOUR_WORKSPACE_ID

Tenant authentication:

/path/to/fastn-mcp-server --space_id YOUR_WORKSPACE_ID --tenant_id YOUR_TENANT_ID --auth_token YOUR_AUTH_TOKEN

Using Manual Installation

API Key authentication:

/path/to/your/uv --directory /path/to/your/fastn-server run fastn-server.py --api_key YOUR_API_KEY --space_id YOUR_WORKSPACE_ID

Tenant authentication:

/path/to/your/uv --directory /path/to/your/fastn-server run fastn-server.py --space_id YOUR_WORKSPACE_ID --tenant_id YOUR_TENANT_ID --auth_token YOUR_AUTH_TOKEN

Troubleshooting

Package Structure Error

If you encounter an error like this during installation:

ValueError: Unable to determine which files to ship inside the wheel using the following heuristics:
The most likely cause of this is that there is no directory that matches the name of your project (fastn).

Quick Fix:

1. Make sure pyproject.toml has the wheel configuration:

[tool.hatch.build.targets.wheel]
packages = ["."]

2. Then install dependencies:

uv pip install "httpx>=0.28.1" "mcp[cli]>=1.2.0"

Support

• Documentation: https://docs.fastn.ai
• Community: https://community.fastn.ai

License

This project is licensed under the terms included in the LICENSE file.