Setup¶

Configure jpx-mcp as an MCP server for Claude Desktop or as a standalone HTTP server.

Installation¶

Install jpx-mcp:

cargo install jpx-mcp

Or use Docker (no installation required).

Transport Modes¶

jpx-mcp supports two transport modes:

Transport	Use Case
`stdio` (default)	Claude Desktop and other MCP clients
`http`	Web applications, remote access

Claude Desktop Configuration¶

Docker (Recommended)¶

The simplest way to run jpx as an MCP server using the dedicated server image:

{
  "mcpServers": {
    "jpx": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "ghcr.io/joshrotenberg/jpx-mcp"]
    }
  }
}

Available for linux/amd64 and linux/arm64.

macOS¶

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

{
  "mcpServers": {
    "jpx": {
      "command": "jpx-mcp"
    }
  }
}

If jpx-mcp is not in your PATH, use the full path:

{
  "mcpServers": {
    "jpx": {
      "command": "/Users/yourname/.cargo/bin/jpx-mcp"
    }
  }
}

Windows¶

Edit %APPDATA%\Claude\claude_desktop_config.json:

{
  "mcpServers": {
    "jpx": {
      "command": "C:\\path\\to\\jpx-mcp.exe"
    }
  }
}

Verify Setup¶

Restart Claude Desktop
Look for the jpx tools in Claude's tool list
Try a simple query:

User: I have this JSON: {"users": [{"name": "alice"}, {"name": "bob"}]}
      Get all the names.

Claude: [Uses jpx.evaluate]
        Result: ["alice", "bob"]

HTTP Transport¶

Run jpx-mcp as an HTTP server for web applications or remote access:

# Start HTTP server on default port 3000
jpx-mcp --transport http

# Custom host and port
jpx-mcp --transport http --host 0.0.0.0 --port 8080

# With request timeout
jpx-mcp --transport http --request-timeout-secs 60

CLI Options¶

jpx-mcp [OPTIONS]

Options:
  -t, --transport <TRANSPORT>       Transport mode [default: stdio] [possible values: stdio, http]
      --strict                      Use standard JMESPath only (no extensions)
  -l, --log-level <LOG_LEVEL>       Log level [default: info]
      --host <HOST>                 HTTP host [default: 127.0.0.1]
  -p, --port <PORT>                 HTTP port [default: 3000]
      --request-timeout-secs <SECS> Request timeout in seconds [default: 30]
  -h, --help                        Print help
  -V, --version                     Print version

Strict Mode¶

To use only standard JMESPath functions (no extensions):

{
  "mcpServers": {
    "jpx": {
      "command": "jpx-mcp",
      "args": ["--strict"]
    }
  }
}

Or with Docker:

{
  "mcpServers": {
    "jpx": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "ghcr.io/joshrotenberg/jpx-mcp", "--strict"]
    }
  }
}

Troubleshooting¶

jpx-mcp not found¶

Make sure jpx-mcp is in your PATH, or use the full path in the config.

Tools not appearing¶

Check the config file syntax (must be valid JSON)
Restart Claude Desktop completely
Check Claude Desktop logs for errors

Permission errors on file access¶

The evaluate_file tool has security restrictions. It only allows access to files in safe directories (not system paths).