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Isthmus MCP Server

@guillermoBallester

Repository

Basic information

Category

Databases

Transports

stdio

Author

guillermoBallester

Submitted by

Guillermo Sasso

About Isthmus MCP Server

A single binary MCP server that gives Claude, Cursor, and any MCP client safe, read-only access to your PostgreSQL database. Runs locally over stdio or HTTP — your credentials never leave your machine.

#postgresdb#masking#mcpserver

Isthmus MCP Server config

Add this server to your MCP-compatible client using the configuration below.

{
  "mcpServers": {
    "isthmus": {
      "command": "isthmus",
      "env": {
        "DATABASE_URL": "postgres://user:pass@localhost:5432/mydb"
      }
    }
  }
}

Isthmus MCP Server tools

Tool list not available yet

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Overview

What is Isthmus?

Isthmus is a local MCP server that gives AI models safe, read-only access to your PostgreSQL database. It runs as a single binary on your machine; credentials never leave.

How to use Isthmus?

Install Isthmus via the install script or Docker, set the DATABASE_URL environment variable, and add it to your MCP client configuration (e.g., Claude Desktop JSON). Then ask your AI questions about your database.

Key features of Isthmus

  • Schema discovery and table description tools
  • Read-only queries with server-side row limits and timeouts
  • Column masking for PII (redact, hash, partial, null)
  • Policy engine that enriches schema with business context
  • SQL validation via AST-level whitelist (only SELECT/EXPLAIN allowed)
  • HTTP transport for web-based clients and remote access
  • OpenTelemetry support for distributed tracing and metrics
  • Works with Claude Desktop, Cursor, Windsurf, VS Code, and ChatGPT Desktop

Use cases of Isthmus

  • Allow an AI assistant to explore and query your PostgreSQL schema without write access
  • Enable safe database analysis in client applications by enforcing read-only queries
  • Protect sensitive PII data by masking columns before results reach the AI
  • Give AI models business context on schema objects so they generate more accurate SQL

Frequently asked questions

1

What databases does Isthmus support?

Isthmus works exclusively with PostgreSQL databases.

2

Is Isthmus read-only?

Yes. Isthmus only allows `SELECT` and `EXPLAIN` statements, enforced via AST-level validation using PostgreSQL’s own parser.

3

How does Isthmus protect PII?

Column masking allows per-column redact, hash, partial, or null masking, enforced server-side before results are returned.

4

What transport protocols does Isthmus support?

Isthmus supports stdio (for desktop MCP clients) and HTTP (for web-based clients and remote access).

5

Which MCP clients are compatible with Isthmus?

Isthmus works with any MCP client, including Claude Desktop, Cursor, Windsurf, Gemini CLI, VS Code, and ChatGPT Desktop.

Comments

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