Schemity MCP ServerVerifiedFeatured

What is Schemity MCP Server?

Schemity MCP Server is a local database MCP server built into Schemity, a desktop database design app. Your agent reads the schema of your PostgreSQL, MySQL, MariaDB, SQL Server or SQLite database through the diagram open in Schemity, checks what a migration would do before it runs, and stages edits you review.

Most database MCP servers hand the agent a connection string and run whatever SQL it writes. Schemity works the other way round: the agent works through the diagram Schemity read from your database, never gets database credentials, and nothing it does writes to a database. Reads change nothing, edits land as unsaved changes in the diagram, and the database is only touched when you run the migration yourself. The server ships inside the closed-source desktop app; the GitHub repository tbson/schemity-mcp holds its documentation, tools.json and example host configs.

How to use Schemity MCP Server?

1. Install Schemity on macOS, Windows or Linux.
2. Open the diagram you want the agent to see. The server sees diagrams open in the Schemity window, not files on disk.
3. Open the MCP panel from the plug icon in the control bar, or with Cmd+Shift+A (macOS) / Ctrl+Shift+A (Windows, Linux). It shows the server status, a connection test and a snippet for each host with the right path for your platform.

The examples below use the macOS path. On Windows and Linux, copy the snippet from the MCP panel.

Hosts connect in one of two ways. stdio hosts start the Schemity binary with --mcp, so they can also launch Schemity when it is closed. HTTP hosts connect to http://127.0.0.1:7332/mcp with a bearer token from the panel, and Schemity must already be open.

Claude Code

claude mcp add --scope user schemity -- "/Applications/Schemity.app/Contents/MacOS/schemity" --mcp

If you registered Claude Code with the older HTTP command, run claude mcp remove --scope user schemity first.

Claude Desktop

Add this to claude_desktop_config.json, then restart Claude Desktop:

{
  "mcpServers": {
    "schemity": {
      "command": "/Applications/Schemity.app/Contents/MacOS/schemity",
      "args": ["--mcp"]
    }
  }
}

Cursor

Keep Schemity open. Add to ~/.cursor/mcp.json, with the token copied from the MCP panel:

{
  "mcpServers": {
    "schemity": {
      "url": "http://127.0.0.1:7332/mcp",
      "headers": { "Authorization": "Bearer <token from the MCP panel>" }
    }
  }
}

Codex

Add to ~/.codex/config.toml:

[mcp_servers.schemity]
command = "/Applications/Schemity.app/Contents/MacOS/schemity"
args = ["--mcp"]

OpenCode takes a local entry in opencode.json with the same command and --mcp.

Key features of Schemity MCP Server

• Works with PostgreSQL, Supabase, MySQL, MariaDB, SQL Server and SQLite, directly or through an SSH tunnel.
• The agent never receives database credentials.
• Impact analysis before a migration runs: lost data, statements that fail on existing rows, table rewrites, locks on large tables, and dependent views and functions.
• Analyzes hand-written or Prisma, Alembic and Flyway migration files without running them.
• Agent edits are staged as unsaved changes and recorded in undo history under the agent's name.
• A plan that deletes something asks you first, naming the agent and listing what it wants to delete.
• No vendor cloud: the HTTP server listens on 127.0.0.1 only, and the bearer token is kept in your OS keychain.

Schemity MCP Server tools

Schemity 2.11.2 exposes 16 tools.

• Read tools (never change anything): open_schemity starts the app or brings it to the front; list_diagrams (call it first), get_schema and get_context_views describe the open diagrams; get_dependencies shows relations into and out of an entity; get_data_dictionary returns the documented schema as Markdown; lint reports conventions, missing indexes and type mismatches.
• Migration impact: get_pending_changes, analyze_impact, analyze_migration_file and count_rows, which runs an exact count as a read-only query when you ask for it.
• Visual review: check_relation_lines finds overlapping or crossing lines; show_preview draws a proposed change on a throwaway read-only canvas.
• Staged edits: propose_changes creates, changes and deletes entities, fields, relations, legends and context views; group_entities groups entities into legends; route_relations reroutes relation lines so they cross less.

Use cases of Schemity MCP Server

• Pre-merge migration review: "Analyze this Prisma migration file and tell me which statements would fail on existing rows."
• Schema discovery: "List the diagrams, then explain how the orders and invoices tables relate."
• Schema design: "Add an audit_log table linked to users," then review the staged change in Schemity and save or undo.
• Documentation: "Export the data dictionary for this diagram as Markdown."
• Clean-up: "Run lint and fix the missing indexes it finds."

Troubleshooting Schemity MCP Server

• "Schemity is not running": only a stdio host can start the app. On an HTTP host such as Cursor, open Schemity yourself and retry.
• 401 Unauthorized: the token was regenerated in the panel. Copy the current one into the host's config.
• Port in use: pick another port in the MCP panel and click Restart.
• A tool says a diagram is "not open": open that diagram in the Schemity window.