Unify SaaS Tool Access via Single API

Fastn MCP Server

Give your AI agents and apps secure, governed access to your customers' tools and systems through one multi-tenant MCP endpoint.

Part of Fastn, the embedded integration platform for SaaS products and AI agents. Fastn MCP Server is a production-ready Model Context Protocol (MCP) gateway that connects AI agents and apps to Slack, Jira, GitHub, Salesforce, HubSpot, Postgres, and 200+ more services, with fully managed auth, governed multi-tenant access, and sub-second execution.

Built on the Fastn SDK, this server exposes MCP tools that any compatible AI platform can use out of the box.

Why Fastn MCP Server?

Quick Start

1. Sign up at app.fastn.ai

Create an account and connect your first connectors (Gmail, Slack, GitHub, etc.).

2. Connect your MCP client

Hosted server (recommended), no installation needed:

https://mcp.live.fastn.ai/shttp

Point any MCP client at this URL. Authentication is handled via MCP OAuth 2.1 automatically. See Client Configuration for Claude Desktop and Cursor examples.

Self-hosted, install and run your own instance:

pip install fastn-mcp-server
fastn-mcp --shttp --port 8000

Connecting to the MCP Server

Endpoints

Use the hosted server (mcp.live.fastn.ai) or your self-hosted instance. Each path exposes a different set of tools:

Examples with the hosted server:

https://mcp.live.fastn.ai/shttp                              # All tools
https://mcp.live.fastn.ai/shttp/tools                           # Fastn tools only
https://mcp.live.fastn.ai/shttp/tools/{project_id}              # Pre-set project
https://mcp.live.fastn.ai/shttp/tools/{project_id}/{skill_id}   # Pre-set project + skill

Authentication

The MCP server supports three authentication methods. Get your credentials from app.fastn.ai.

MCP OAuth 2.1 (Recommended)

Standard MCP OAuth flow with PKCE. The server bridges to Fastn's identity provider automatically. Just point your client at the URL, you'll be prompted to authenticate:

{
  "mcpServers": {
    "tools": {
      "url": "https://mcp.live.fastn.ai/shttp"
    }
  }
}

Token / API Key

Pass a Fastn auth token or API key via the Authorization header in your MCP client config:

{
  "mcpServers": {
    "tools": {
      "url": "https://mcp.live.fastn.ai/shttp",
      "headers": {
        "Authorization": "Bearer <your-token-or-api-key>"
      }
    }
  }
}

You can also pass x-project-id to scope requests to a specific project:

{
  "mcpServers": {
    "tools": {
      "url": "https://mcp.live.fastn.ai/shttp",
      "headers": {
        "Authorization": "Bearer <your-token-or-api-key>",
        "x-project-id": "<your-project-id>"
      }
    }
  }
}

For local stdio transport, pass credentials as environment variables:

{
  "mcpServers": {
    "tools": {
      "command": "fastn-mcp",
      "args": ["--stdio"],
      "env": {
        "FASTN_API_KEY": "your-api-key",
        "FASTN_PROJECT_ID": "your-project-id"
      }
    }
  }
}

MCP Tools

The server exposes these tools to AI agents:

Fastn Tools

Workflow: Browse connectors → list_connectors. Execute an action → find_tools → execute_tool. If find_tools returns nothing relevant → list_connectors (connector may need connecting).

Flow Management

Configuration

Architecture

AI Agent (Claude, Cursor, Lovable)
    │
    ▼
MCP Protocol (stdio / SSE / Streamable HTTP)
    │
    ▼
┌─────────────────────────────┐
│   Fastn MCP Server          │
│   ┌───────────────────────┐ │
│   │ Tool Discovery        │ │  find_tools, list_connectors
│   │ Tool Execution        │ │  execute_tool
│   │ Flow Management       │ │  list/run/delete/create flows
│   │ Auth & Config         │ │  OAuth 2.1, custom JWT
│   └───────────────────────┘ │
└─────────────────────────────┘
    │
    ▼
Fastn SDK → Fastn API
    │
    ▼
250+ Connectors (Slack, Jira, GitHub, Salesforce, Postgres, ...)

Connectors provide tools. Flows compose tools. Agents run flows and tools with reasoning.

Client Configuration

The JSON examples above work with any MCP client. Here are the config file locations:

For Cursor, use the /shttp/tools endpoint to expose only Fastn tools (recommended for coding assistants):

{
  "mcpServers": {
    "tools": {
      "url": "https://mcp.live.fastn.ai/shttp/tools"
    }
  }
}

Self-Hosting

Transport Modes

stdio (local), For pipe-based clients:

fastn-mcp --stdio
fastn-mcp --stdio --mode tools                          # Fastn tools only
fastn-mcp --stdio --mode tools --project ID              # Fastn tools + pre-set project
fastn-mcp --stdio --mode tools --project ID --skill ID   # Fastn tools + pre-set project and skill

SSE + Streamable HTTP (remote), For web-based AI platforms:

fastn-mcp --sse --shttp --port 8000

OAuth Setup

Remote transports use MCP OAuth 2.1 by default. The server implements RFC 9728 Protected Resource Metadata:

fastn-mcp --sse --shttp --port 8000
# OAuth endpoints auto-configured at /.well-known/oauth-protected-resource

Set the public URL for OAuth metadata:

fastn-mcp --sse --shttp --port 8000 --server-url https://mcp.example.com

To disable OAuth for local development:

fastn-mcp --sse --port 8000 --no-auth

Docker

docker build -t fastn-mcp .
docker run -p 8000:8000 fastn-mcp

docker compose up -d

Environment Variables

Server configuration for self-hosted deployments:

FASTN_MCP_PORT=8000
FASTN_MCP_HOST=0.0.0.0
FASTN_MCP_SERVER_URL=https://your-public-url
FASTN_MCP_TRANSPORT=both
FASTN_MCP_NO_AUTH=false
FASTN_MCP_VERBOSE=false

Local Development with ngrok

For local development and testing only, use ngrok to expose your local server:

# Terminal 1: Start the MCP server
fastn-mcp --shttp --port 8000 --verbose

# Terminal 2: Start ngrok tunnel
ngrok http 8000

Then restart with the ngrok URL so OAuth metadata resolves:

fastn-mcp --shttp --port 8000 \
  --server-url https://abc123.ngrok-free.dev \
  --verbose

For production, deploy with Docker behind a reverse proxy with a real domain.

Development

Setup

git clone https://github.com/fastn-ai/fastn-mcp.git
cd fastn-mcp
python -m venv .venv
source .venv/bin/activate
pip install -e ".[dev]"

Run Tests

pytest tests/ -q

Project Structure

fastn-mcp/
├── fastn_mcp/
│   ├── __init__.py          # Package metadata
│   ├── __main__.py          # CLI entry point
│   ├── server.py            # MCP server, tools, handlers, routing
│   ├── auth.py              # OAuth 2.1 provider (RFC 9728)
│   └── tools/               # Tool utilities
├── tests/
│   ├── test_server.py       # 185+ tests covering all tools and transports
│   └── conftest.py          # Test fixtures
├── Dockerfile               # Production container
├── docker-compose.yml       # Docker Compose for deployment
├── pyproject.toml           # Python project configuration
└── README.md

CLI Reference

fastn-mcp [OPTIONS]

Transport:
  --stdio          Use stdio transport (Claude Desktop, Cursor)
  --sse            Enable SSE transport
  --shttp          Enable Streamable HTTP transport

Server:
  --host HOST      Bind address (default: 0.0.0.0)
  --port PORT      Port number (default: 8000)
  --no-auth        Disable OAuth (development only)
  --server-url URL Public URL for OAuth metadata

Mode:
  --mode {agent,tools} Tool mode for stdio: "agent" (all tools) or "tools" (Fastn tools only)
  --project ID     Pre-set project ID for stdio
  --skill ID       Pre-set skill ID for stdio (requires --project)

Debug:
  -v, --verbose    Enable debug logging

Supported Connectors

Fastn provides 250+ pre-built connectors including:

Communication: Slack, Microsoft Teams, Discord, Gmail, Outlook, SendGrid, Twilio

Project Management: Jira, Linear, Asana, Trello, Monday.com, ClickUp, Notion

Development: GitHub, GitLab, Bitbucket, PagerDuty, Sentry, Datadog

CRM & Sales: Salesforce, HubSpot, Pipedrive, Zoho CRM

Databases: PostgreSQL, MySQL, MongoDB, Redis, Supabase, Firebase

Cloud: AWS, Google Cloud, Azure, Cloudflare

Finance: Stripe, QuickBooks, Xero

And 200+ more, browse the full catalog at fastn.ai/integrations

Links

• Fastn Platform
• Fastn SDK
• MCP Specification
• Documentation