Warrant MCP Server

Name: Warrant MCP Server
Author: io.github.s0fractal

io.github.s0fractal/warrant

Repository Registry

What is the Warrant MCP server?

Record an agent's decisions with reasons anyone can re-execute offline — verify recomputes them.

How to install Warrant

Copy-paste configuration for popular MCP clients.

transport: stdio

Config generated by PluginBench — verify against the source before use.

Environment / auth

WARRANT_STORE
Absolute path to the warrant store this server files into and verifies. Defaults to .warrants relative to the server process's working directory, which an MCP host does not guarantee.
WARRANT_KEY
secret
Ed25519 signing key. If unset, one is generated next to the store on the first filing and the result says so; any process that can read it can sign as this actor.
WARRANT_ACTOR
Actor id written into filed warrants. Defaults to mcp-client@<hostname>.

Claude Desktop

~/Library/Application Support/Claude/claude_desktop_config.json

{
  "mcpServers": {
    "warrant": {
      "command": "uvx",
      "args": [
        "warrant-verify"
      ],
      "env": {
        "WARRANT_STORE": "<YOUR_WARRANT_STORE>",
        "WARRANT_KEY": "<YOUR_WARRANT_KEY>",
        "WARRANT_ACTOR": "<YOUR_WARRANT_ACTOR>"
      }
    }
  }
}

Cursor

~/.cursor/mcp.json

{
  "mcpServers": {
    "warrant": {
      "command": "uvx",
      "args": [
        "warrant-verify"
      ],
      "env": {
        "WARRANT_STORE": "<YOUR_WARRANT_STORE>",
        "WARRANT_KEY": "<YOUR_WARRANT_KEY>",
        "WARRANT_ACTOR": "<YOUR_WARRANT_ACTOR>"
      }
    }
  }
}

Windsurf

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "warrant": {
      "command": "uvx",
      "args": [
        "warrant-verify"
      ],
      "env": {
        "WARRANT_STORE": "<YOUR_WARRANT_STORE>",
        "WARRANT_KEY": "<YOUR_WARRANT_KEY>",
        "WARRANT_ACTOR": "<YOUR_WARRANT_ACTOR>"
      }
    }
  }
}

VS Code

.vscode/mcp.json

{
  "servers": {
    "warrant": {
      "type": "stdio",
      "command": "uvx",
      "args": [
        "warrant-verify"
      ],
      "env": {
        "WARRANT_STORE": "<YOUR_WARRANT_STORE>",
        "WARRANT_KEY": "<YOUR_WARRANT_KEY>",
        "WARRANT_ACTOR": "<YOUR_WARRANT_ACTOR>"
      }
    }
  }
}

Claude Code

claude mcp add warrant --env WARRANT_STORE=<YOUR_WARRANT_STORE> --env WARRANT_KEY=<YOUR_WARRANT_KEY> --env WARRANT_ACTOR=<YOUR_WARRANT_ACTOR> -- uvx warrant-verify