grains-mcp

An MCP server for Grains — build and deploy a hosted agent to grains.run without leaving Claude.

It's a thin client over the Grains control-plane API. Every tool call acts as one Grains user, authenticated by that user's deploy token.

Tools

Setup

Hosted (recommended) — nothing to install, no token to paste; Claude Code opens your browser to sign in with GitHub (OAuth 2.1 + PKCE, dynamic client registration):

claude mcp add --transport http grains https://mcp.grains.run/mcp

Or with a deploy token (from api.grains.run/welcome) as a header, skipping the browser flow:

claude mcp add --transport http grains https://mcp.grains.run/mcp \
  --header "Authorization: Bearer grains_dt_your_token_here"

Local — run this same package on your machine (needs uv):

claude mcp add grains \
  --env GRAINS_API_URL=https://api.grains.run \
  --env GRAINS_DEPLOY_TOKEN=grains_dt_your_token_here \
  -- uvx grains-mcp

{
  "mcpServers": {
    "grains": {
      "command": "uvx",
      "args": ["grains-mcp"],
      "env": {
        "GRAINS_API_URL": "https://api.grains.run",
        "GRAINS_DEPLOY_TOKEN": "grains_dt_your_token_here"
      }
    }
  }
}

Then, in Claude: "scaffold a URL-summarizer agent and deploy it to Grains." Claude calls grains_scaffold, writes the files, calls grains_deploy, and you can grains_invoke it — all in one conversation.

Transports

• stdio (default) — for the Claude Code config above.
• streamable-http — grains-mcp --http --port 8080, for hosting at mcp.grains.run (hosted OAuth-backed deployment is a follow-up; today the server authenticates with the deploy token from its env).