LLM Kit
LLM Kit
The FastComments LLM Kit helps AI coding assistants like Claude, ChatGPT, and Cursor understand and integrate with FastComments by providing them access to our complete documentation through a simple search API.
By adding a snippet to your project's AGENT.md or CLAUDE.md file, you enable AI assistants to quickly search and retrieve relevant FastComments documentation, making implementation faster and more accurate.
Get the LLM Kit 
Add this snippet to your project's AI assistant configuration files (like AGENT.md or CLAUDE.md) that teaches AI coding assistants how to search and access FastComments documentation.
This way your AI assistant can easily get up-to-date information and provide more accurate implementations in less time.
Usage Example
When using an AI assistant like Claude Code or Cursor, you can ask questions like:
- "How do I install FastComments on React?"
- "Show me how to configure SSO with FastComments"
- "What are the FastComments API authentication options?"
The AI assistant will automatically search the documentation using the provided API endpoint and give you accurate, up-to-date answers based on the official documentation.
MCP Server
FastComments runs a hosted Model Context Protocol (MCP) server so AI assistants and agentic clients can call the FastComments API directly. Every tool the MCP server exposes is auto-generated from the public OpenAPI spec, so anything the REST API can do, an MCP client can do.
The endpoint is stateless and streamable-HTTP based. There is no session to keep alive and no server-side state per client.
Endpoint
Connect with OAuth
Any MCP client that supports remote servers with OAuth (Claude, ChatGPT, Claude Code, Cursor, and others) can connect to the endpoint above with no setup on the FastComments side. The client registers itself through Dynamic Client Registration or identifies itself with a Client ID Metadata Document, opens a browser so you can sign in to FastComments and approve access, and receives a token bound to the account you were signed in to.
The discovery documents are at the standard locations:
Your user needs the API Admin permission on the account to approve a connection. If you manage several accounts, switch to the right one in the dashboard before approving.
A client can request the read scope, the write scope, or both. A client that requests nothing gets both. Tools that change data are not offered to a read-only token.
The dashboard has a setup helper with ready-to-paste snippets. Open Integrate -> MCP Server, or visit it directly:
Claude Code
Register the FastComments server with one command, then run /mcp inside a session to sign in and list the available tools:
Cursor and other config-file clients
Add this block to your client's MCP servers config (mcp.json for Cursor). The client opens a browser to sign in on first use.
Revoking access
Every approved connection is listed under Integrate -> Connected Apps in the dashboard. Revoking one invalidates every token that application holds. Applications register themselves when they connect and FastComments does not review them, so revoke anything you do not recognize.
Using the token with the REST API
The access token an MCP client obtains is a regular FastComments API credential. It works on every /api/v1 endpoint as a bearer token, so an application that connected through MCP can also call the REST API directly:
The tenant is implied by the token. A tenantId may still be passed but it must match. GET requests need the read scope and everything else needs the write scope.
Connect with an API key
Clients that cannot complete a browser sign-in, such as headless servers, can authenticate with an API key instead. Pass tenantId and API_KEY as query parameters, or as the x-tenant-id and x-api-key HTTP headers if your client supports custom headers:
The setup page generates this URL for each of your API keys.
Security
An endpoint URL that contains an API key is a secret: do not paste it into public chats, screenshots, or commits. If a key is exposed, rotate it on the API Keys page in your dashboard. OAuth tokens carry no such risk because they are bound to one application and can be revoked from Connected Apps.
Let an Agent Set Up Your Account
A coding agent such as Claude Code, Cursor, or an MCP-based assistant can set up FastComments for you without you filling in the signup form. This is useful when you ask an agent to "add comments to my site" and you do not have an account yet.
How it works
- The agent creates a new account and receives an API key and a claim link. The API key works right away, so the agent can configure the account and install the widget on your site.
- The agent gives you the claim link. Open it in your browser, log in or create a login, and confirm the claim. The account is then yours: you manage it, its billing, and its API keys from the dashboard. The page lists the API key the agent holds so you can revoke it if you no longer want the agent, or whoever runs it, to have access.
- If nobody opens the claim link within 72 hours, the account and its key are deleted. Ask the agent to create a new one.
Until it is claimed, the account has the same limits as a normal free trial.
If you already have an account
Each login owns one account. If you open a claim link while logged in to an existing account, the page lets you choose:
- Attach to my account makes the new account a managed tenant of the one you are logged in to. This needs a paid plan with white labeling, and the new tenant's usage is billed to your account.
- Sign out and claim with another login signs you out and brings you back to the claim page so you can claim it with a different login.
For agent authors
The agent instructions at fastcomments.com/agents.md describe the account creation call, the fields in the response, and how to hand the claim link to the person you are working for. The call needs no API key and is rate limited per IP address.