Habitica

Habitica Model Context Protocol server built with Effect v4 beta.

The server exposes typed Habitica read/write tools over stdio. Tool handlers depend on an Effect HabiticaGateway port; the live adapter uses Effect HTTP and schema-decodes Habitica API responses at the boundary.

Requirements

• Node.js >=22.12.0
• pnpm >=10

This repo uses pnpm rather than bun because the server runs on Node stdio, the lockfile is already deterministic, and the Effect MCP docs target Node runtime primitives.

Install

pnpm add -g habitica-mcp@alpha

For local development:

pnpm install

Required variables:

• HABITICA_USER_ID
• HABITICA_API_TOKEN
• HABITICA_CLIENT_ID
• HABITICA_API_BASE_URL defaults to https://habitica.com/api/v3

For a local checkout, copy the example env file and fill in your Habitica credentials:

cp .env.example .env

Commands

pnpm dev          # run the stdio MCP server from TypeScript
pnpm build        # emit dist
pnpm check        # full deterministic gate used by Lefthook
pnpm test         # run unit tests
pnpm test:coverage # run unit tests with 100% coverage threshold
pnpm e2e          # run strict effect-bdd Gherkin tests
pnpm mutation     # run Stryker with 100% mutation threshold

pnpm e2e is a deterministic fake-gateway suite. It exercises the full MCP tool handler surface without live Habitica credentials or network calls.

Deterministic Gate

pnpm check runs build, typecheck, suppression policy, deterministic scope policy, custom oxlint RuleTester coverage, oxlint, format check, 100% unit coverage, strict effect-bdd Gherkin e2e, 100% Stryker mutation coverage for the deterministic core, and knip.

Lefthook runs pnpm check on pre-commit:

pnpm prepare

GitHub Actions runs the same pnpm check gate on pushes to main and pull requests.

Tool Surface

HelloWorldTool returns a deterministic greeting and does not require Habitica credentials. Use it as the first MCP smoke test.

Core tools cover profile, stats, tasks, tags, checklists, and notifications. Expanded tools cover rewards, inventory, shop items, pets, mounts, and skills.

Mutating tools use explicit verb names such as CreateTaskTool, UpdateTaskTool, DeleteTaskTool, ScoreTaskTool, ReadNotificationTool, BuyRewardTool, and CastSkillTool. They request approval and return typed structured results.

Architecture Guardrails

• MCP stdout is protocol-owned; logs go to stderr.
• Tools import HabiticaGateway, not HabiticaHttpAdapter or raw route strings.
• Habitica credentials and auth headers must never be logged.
• Every Tool.make call declares a success schema.
• Deterministic modules must be listed in coverage and mutation scope.

MCP Config

Use the local TypeScript entrypoint while developing:

{
  "mcpServers": {
    "habitica": {
      "command": "pnpm",
      "args": ["--dir", "/absolute/path/to/habitica-mcp", "dev"]
    }
  }
}

After pnpm build, use the package binary:

{
  "mcpServers": {
    "habitica": {
      "command": "node",
      "args": ["/absolute/path/to/habitica-mcp/dist/main.js"]
    }
  }
}

After installing from npm, use the binary:

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

Publishing

This package is intentionally pre-1.0. Publish early builds with the manual Publish GitHub Actions workflow. It uses the repository NPM_TOKEN secret, runs pnpm check, and publishes with npm provenance on the alpha dist-tag.

Equivalent local command:

pnpm check
npm publish --tag alpha --provenance

prepack builds dist/; publishConfig marks the package public and enables npm provenance.