What is Isthmus?
Isthmus is an open-source Model Context Protocol (MCP) server that gives AI models direct access to your PostgreSQL database. It runs locally as a single binary, supports both stdio and HTTP transports, and requires no cloud services. Point your AI client at Isthmus, and it can discover your schema, understand table relationships, analyze data distributions, and execute read-only SQL queries — all with built-in safety guardrails.Tools
Isthmus exposes three MCP tools that let AI models explore and query your database:discover
Full database landscape: all schemas with their tables, sizes, row counts, and column counts in a single call.
describe_table
Complete table analysis: columns, types, foreign keys, indexes, column statistics, sample rows, and index usage.
query
Execute read-only SQL queries with optional EXPLAIN plans.
Supported clients
Isthmus works with any MCP client. Most clients use the default stdio transport; clients that require HTTP can use the HTTP transport.- Claude Desktop — stdio
- Cursor — stdio
- Windsurf — stdio
- Gemini CLI — stdio
- VS Code (Cline & Continue) — stdio
- ChatGPT Desktop — HTTP (
--transport http)