What is mcp-postgres CLAUDE.md?

A PostgreSQL server for the Model Context Protocol, which is a standard way for AI assistants to use external tools. It lets agents query databases and inspect tables, schemas, relationships, and foreign keys.

Use it to let an agent inspect or query a PostgreSQL database locally over standard input/output or through an HTTP server.

It removes the need to build separate database access tools for an AI agent and can optionally apply user permissions through token-based authentication.

How gldc/mcp-postgres configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to gldc/mcp-postgres. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/gldc/mcp-postgres/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/gldc/mcp-postgres

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/gldc/mcp-postgres/claude-md/github.svg)](https://agentmods.dev/instructions/gldc/mcp-postgres/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/gldc/mcp-postgres/claude-md"><img src="https://agentmods.dev/badge/instructions/gldc/mcp-postgres/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/gldc/mcp-postgres/claude-md"><img src="https://agentmods.dev/badge/instructions/gldc/mcp-postgres/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 843 This file is loaded in full into every session.

When invoked 843 The same file — it is already loaded in full.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00843	$0.00843
Opus 5.5	$0.00337	$0.00337
Sonnet 5.5	$0.00169	$0.00169
Haiku 4.5	$0.00084	$0.00084

Measured 2mo ago against content hash f361a29fc94b, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

mcp-postgres CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 75 lines

How it starts

The opening of the file, as written. The whole thing — 75 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

What This Is

A PostgreSQL MCP (Model Context Protocol) server that lets AI agents interact with Postgres databases. It exposes database tools (query, list tables/schemas, describe tables, foreign keys, relationships) via the FastMCP framework with async connection pooling. Optional JWT/JWKS auth with YAML-based permissions for multi-user environments.

Commands

# Setup
python -m venv .venv && source .venv/bin/activate
pip install -r requirements.txt
pip install -r dev-requirements.txt

# Run MCP server (stdio, local dev)
python postgres_server.py --conn "postgresql://user:pass@host:5432/db"

# Run MCP server (HTTP transport)
python postgres_server.py --transport streamable-http --host 127.0.0.1 --port 8000

# Tests
pytest -q
pytest tests/test_tools.py                          # unit tests
pytest tests/test_tools.py::test_query_no_dsn_async  # single test

# Linting
ruff check .

Architecture

Single-file async MCP server:

postgres_server.py — Uses FastMCP from mcp[cli] to register tools. Connects to Postgres via psycopg with AsyncConnectionPool from psycopg_pool. Supports three transports: stdio (local), sse, streamable-http (remote/Railway). Lifespan context manager owns the pool, config, and permissions.

Key components:

ServerConfig — Dataclass parsed from CLI args + env vars
AppContext — Lifespan-scoped context holding pool, config, permissions
Permissions / RolePermissions — YAML-based role/schema/table/operation enforcement
JWKSTokenVerifier — Optional JWT verification against external IdP JWKS endpoint

Tools: query, list_schemas, list_tables, describe_table, get_foreign_keys, find_relationships, server_info, db_identity

Two modes:

No-auth (default): Shared connection pool, no permission checks
Auth-enabled: JWT tokens verified via JWKS, permissions enforced per-user from permissions.yaml

Read the full file on GitHub · 75 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 75 lines · 843 tokens per session scan A f361a29fc94b

Subscribe to this mod's changes

mcp-postgres CLAUDE.md is an instructions file published in the GitHub repository gldc/mcp-postgres (15 stars, last pushed 8mo ago), licensed MIT. It adds 843 tokens to every session, about $0.0034 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Databases PostgreSQL

mcp-postgres CLAUDE.md next to 6 instructions from other repositories
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mcp-postgres: Instructions file for Claude Code