Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add instructions/gldc/mcp-postgres/claude-mdgit clone --depth 1 https://github.com/gldc/mcp-postgresWhat 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 | $0.00843 | $0.00843 |
| Opus 5 | $0.00421 | $0.00421 |
| Sonnet 5 | $0.00169 | $0.00169 |
| Haiku 4.5 | $0.00084 | $0.00084 |
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 2d 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.
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— UsesFastMCPfrommcp[cli]to register tools. Connects to Postgres viapsycopgwithAsyncConnectionPoolfrompsycopg_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 varsAppContext— Lifespan-scoped context holding pool, config, permissionsPermissions/RolePermissions— YAML-based role/schema/table/operation enforcementJWKSTokenVerifier— 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
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.
- 2d ago First seen · 75 lines · 843 tokens per session scan A f361a29fc94b
mcp-postgres CLAUDE.md is an instructions file published in the GitHub repository gldc/mcp-postgres (15 stars, last pushed 6mo ago), licensed MIT. It adds 843 tokens to every session, about $0.0042 per session on Opus 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.
Other instructions, from other repositories
expense-budget-tracker AGENTS.md
Instructions for kirill-markin/expense-budget-tracker, covering expense-budget-tracker, rules, components, supported clients and key paths.
postgres-skills AGENTS.md
Instructions for neondatabase/postgres-skills, covering agents.md, repository overview, creating a new skill, directory structure and naming conventions.
pg_exporter AGENTS.md
Instructions for nbari/pg_exporter, covering agents.md, project shape, first steps, devpod workflow (preferred) and local commands.
db-connect-mcp CLAUDE.md
Instructions for yugui923/db-connect-mcp, covering claude.md, project overview, pre-commit requirements, 1. format code and 2. lint code.
Synapsor-Runner AGENTS.md
Instructions for Synapsor/Synapsor-Runner, covering agent guide for synapsor runner, first commands, what not to change casually, how the flow works and add a capability without reading dist/.
ai-dba-workbench CLAUDE.md
Claude Code instructions for pgEdge/ai-dba-workbench, covering claude standing instructions, primary agent role, trivial-edit carve-out, project structure and key files.