MCP Overview

pREST exposes a PostgreSQL MCP server over HTTP so AI agents can discover schemas and read data through the same process that serves your REST API.

Requires pREST v2.1.0+.

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Two layers

Layer	What it is	What it does
HTTP MCP endpoint	/_mcp on prestd	Implements MCP tools, catalog discovery, and read queries
Stdio adapter	prest-mcp binary	Forwards JSON-RPC between stdin/stdout and POST /_mcp

The adapter is a transport bridge only. It does not introspect schemas, generate SQL, or implement tools — those live in pREST.

MCP client / AI IDE
        ↓ stdio (NDJSON JSON-RPC)
prest-mcp
        ↓ HTTP POST
http://localhost:3000/_mcp
        ↓
pREST → PostgreSQL

Concern	Native /_mcp	prest-mcp adapter
Transport	HTTP on the pREST server	Stdio process that proxies to HTTP
Tools / SQL	Implemented in pREST	None — forwards JSON-RPC as-is
When to use	HTTP-capable MCP clients	Clients that only launch stdio servers
Extra process	No	Yes — one lightweight binary

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Security defaults for AI

• Prefer a read-only PostgreSQL role for agent workflows — see Read-only PostgreSQL for AI.

• MCP tools in v2.1.0 are read-only (no insert/update/delete/DDL). REST may still allow writes on the same server.

• Do not expose unauthenticated /_mcp publicly.

• Prefer local or private-network pREST for development.

• When auth is enabled, pass a JWT via PREST_MCP_TOKEN (adapter) or Authorization (HTTP).

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Environment variables (adapter)

Variable	Required	Default	Description
PREST_MCP_URL	yes	—	URL of the HTTP MCP endpoint, e.g. http://localhost:3000/_mcp
PREST_MCP_TOKEN	no	—	Bearer token when pREST auth is enabled
PREST_MCP_TIMEOUT_MS	no	30000	HTTP timeout in milliseconds

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Next steps

• Install pREST MCP Adapter

• Use with Cursor · VS Code and Copilot · Claude Desktop · Other AI tools

• Protocol and tools reference: MCP over HTTP

Related documentation

• AI and MCP landing

• pREST for Cursor plugin

• pREST for OpenClaw plugin

• v2.1.0 release notes