harold-mcp

Harold MCP tools:

• Github repository: https://github.com/demiourgoi/harold/
• Documentation https://demiourgoi.github.io

What is this?

harold-mcp is an MCP server that gives AI coding assistants tools for working with the Maude specification and verification language.

Harold MCP Tools

• maude_program_diagnostics(path) — diagnoses a Maude source file by loading it into the Maude interpreter and reporting every problem it finds, including warnings Maude can recover from. Returns a structured, LSP-style result: a success flag (true only when the file loads with no warnings and no errors), per-severity counts, and one diagnostic per problem with a 1-based line range (range is null for whole-file problems). Use it to check whether a Maude program is well formed, and to get a list of issues to fix.

Planned tools: running Maude programs, and a vector index of the Maude documentation for retrieval-augmented generation (RAG).

Installation

• Install uv
• Run uvx harold-mcp --version

To update run uvx harold-mcp@latest --version.
If you want to run a specific version, check the release history in PyPI use uvx harold-mcp@VERSION, e.g. uvx harold-mcp@0.0.2.

The maude dependency bundles the Maude interpreter (built against Maude 3.5.1), so there is nothing else to install.

Then setup the harold-mcp command defined on pyproject.toml as an MCP server for your IDE.
For example, for Zed add the following to ~/.config/zed/settings.json:

  "context_servers": {
    "harold": {
      "enabled": true,
      "remote": false,
      "command": "uvx harold-mcp",
      "args": [],
      "env": {}
    }
  },
  ...

for opencode (useful for automated testing) add the following to ~/.config/opencode/opencode.jsonc:

  "mcp" : {
    "harold": {
      "type": "local",
      "command": ["uvx harold-mcp"],
      "enabled": true,
      "environment": {}
    }
  }

for Cline (useful for manual testing and Maude programming) add the following to ~/.cline/data/settings/cline_mcp_settings.json:

  "mcpServers" : {
    "harold": {
      "command": "uvx harold-mcp",
      "args": [],
      "disabled": false,
      "autoApprove": [],
      "env": {}
    }
  }

Configuration

The server is configured through environment variables (HAROLD_* prefix) set in the MCP server configuration:

Invalid values (e.g. HAROLD_MAUDE_WORKERS=0) make the server fail fast at startup.

Development

Contributions are welcome! See CONTRIBUTING.md for the contribution workflow, and DEVELOPER_GUIDE.md for the development environment and release process.

Repository initiated with osprey-oss/cookiecutter-uv.