Fastn Server

What is Fastn Server about?

Fastn Server enables dynamic registration and execution of tools defined by APIs. It acts as a unified backend that connects to external services (e.g., Slack, Notion, HubSpot) and AI assistants such as Claude and Cursor, allowing developers to invoke these tools through a consistent MCP interface.

How to use Fastn Server?

1. Install – either via pip install fastn-mcp-server (recommended) or by cloning the repo and installing dependencies with UV.
2. Configure credentials – obtain an API key or tenant credentials from your Fastn workspace.
3. Run the server – use the installed command or uv run fastn-server.py with the appropriate flags (--api_key/--space_id or --tenant_id/--auth_token).
4. Integrate – add the server command to the configuration files of Claude, Cursor, or any MCP‑compatible client.

Key Features of Fastn Server

• Integrated platform support for services like Slack, Notion, HubSpot, etc.
• Flexible authentication: API‑key or tenant‑based.
• Comprehensive logging for troubleshooting.
• Robust error handling for various failure scenarios.
• Ready‑to‑use integration snippets for Claude.ai and Cursor.ai.
• Supports Python 3.10+ and can be installed as a pip package or via manual UV setup.

Use Cases of Fastn Server

• Enterprise workflow automation – register internal tools and expose them through a single MCP endpoint.
• AI‑assistant extensions – let Claude or Cursor call custom Fastn‑registered services directly from the chat UI.
• Third‑party SaaS integration – connect Slack, Notion, HubSpot, etc., without writing separate adapters.
• Rapid prototyping – spin up a local server with a single command to test new tool definitions.

FAQ from the Fastn Server

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 repository and use UV to create a virtual environment and install dependencies.

Q: How do I choose between API‑key and tenant authentication? A: API‑key is ideal for single‑workspace usage; tenant authentication is recommended for multi‑tenant or enterprise scenarios.

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

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

Then reinstall the dependencies.

Q: Where can I find documentation and community support? A: Documentation at https://docs.fastn.ai and community at https://community.fastn.ai.

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.