Mini App MCP server

mini-app-mcp

Agent-First CRUD store MCP server — schema.yaml driven, SQLite backend, multi-table in a single daemon.

What it does

mini-app-mcp is a lightweight MCP server that manages one or more SQLite tables in a single running process. The shape of each table is defined entirely by a schema.yaml file; no migrations, no REST API, no GUI. CRUD is exposed exclusively as MCP tools, making it a natural backend for agents that need structured persistent storage.

Design principles

• schema.yaml as sole schema authority — field names, types, and required constraints are read from YAML at startup. No field is hard-coded in application code.
• Multi-table in one daemon — a single server process discovers and mounts all tables found under the configured User and Project scope directories. A dedicated legacy mode (MINIAPPSCHEMA + MINIAPPDB) preserves the original single-table behaviour.
• MCP-only entry point — there is no HTTP/REST/CLI CRUD interface. All reads and writes go through MCP tools.
• Structured JSON errors — every error response carries a machine-readable code field so agents can handle failures programmatically.

schema.yaml format

table: issues
title: "Issue tracker"
description: "Tracks bugs and feature requests for a project."
fields:
  - name: title
    type: string
    required: true
    description: "Short one-line summary of the issue."
  - name: state
    type: string
    required: false
  - name: tags
    type: array
    required: false

The optional title and description keys at the table level provide human- and AI-readable metadata about the table. Each field entry may also carry an optional description string. All three keys follow the OpenAPI 3.1 / JSON Schema 2020-12 naming convention and are included in info tool output and the schema://json resource.

Supported types: string, number, boolean, array, object.

Configuration

Multi-table mode (recommended)

Tables are discovered at startup by scanning both directories. Project-scope definitions take precedence over User-scope definitions for the same table name.

Legacy single-table mode

When MINIAPPSCHEMA and MINIAPPDB are set the server starts in legacy mode, mounting exactly one table. The table argument on all tools may be omitted in this mode.

All variables can also be placed in a .mini-app-mcp.env file in the working directory.

MCP tools

All tools accept an optional table argument that selects the target table. In multi-table mode the argument is required; omitting it returns error code TABLEREQUIRED. Supplying an unknown table name returns error code TABLENOT_FOUND. In legacy single-table mode the argument may be omitted.

Shortened. The full README is on GitHub.