rmcp-postgres

A PostgreSQL MCP (Model Context Protocol) server built with rmcp, the Rust MCP SDK.

Provides comprehensive PostgreSQL database access through MCP tools for querying, inserting, updating, deleting, and inspecting database schemas.

Features

Full CRUD Operations: Query, insert, update, and delete data
Schema Inspection: List tables, describe schemas, check existence
Relationship Discovery: Explore foreign key relationships
Safety Limits: Built-in protections for bulk operations
Configurable: Flexible database connection configuration
Library + Binary: Use as a standalone server or integrate into your own Rust projects

Installation

From crates.io (coming soon)

cargo install rmcp-postgres

From source

git clone https://github.com/sqrew/rmcp-postgres
cd rmcp-postgres
cargo build --release

The binary will be at target/release/rmcp-postgres.

Usage

As a Standalone Server

Set your PostgreSQL connection string and run:

# Using environment variable
export POSTGRES_CONNECTION_STRING="host=localhost user=postgres dbname=mydb password=secret"
rmcp-postgres

# Using command line argument
rmcp-postgres --db-config "host=localhost user=postgres dbname=mydb password=secret"

As a Library

Add to your Cargo.toml:

[dependencies]
rmcp-postgres = "0.1"
rmcp = { version = "0.12", features = ["server"] }
tokio = { version = "1", features = ["full"] }

Use in your code:

use rmcp::service::ServiceExt;
use rmcp_postgres::PostgresServer;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    // Create server with connection string
    let server = PostgresServer::new("host=localhost user=postgres dbname=mydb");

    // Serve over stdio (for MCP)
    let (stdin, stdout) = (tokio::io::stdin(), tokio::io::stdout());
    server.serve((stdin, stdout)).await?;

    Ok(())
}

Claude Desktop Configuration

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):

{
  "mcpServers": {
    "postgres": {
      "command": "rmcp-postgres",
      "env": {
        "POSTGRES_CONNECTION_STRING": "host=localhost user=postgres dbname=mydb password=secret"
      }
    }
  }
}

Or if installed from source:

{
  "mcpServers": {
    "postgres": {
      "command": "/path/to/rmcp-postgres/target/release/rmcp-postgres",
      "env": {
        "POSTGRES_CONNECTION_STRING": "host=localhost user=postgres dbname=mydb"
      }
    }
  }
}

Available Tools

Data Operations

query_data - Execute SELECT queries and return JSON results
insert_data - Insert rows into tables
update_data - Update rows with WHERE conditions (safety limit: 1000 rows)
delete_data - Delete rows with WHERE conditions (safety limit: 1000 rows)
execute_raw_query - Execute any SQL query (use with caution)

Schema Inspection

list_tables - List all tables in the database
get_schema - Get column information for tables
describe_table - Get detailed table info including indexes and constraints
table_exists - Check if a table exists
column_exists - Check if a column exists in a table

Utilities

count_rows - Count rows in a table with optional WHERE conditions
get_table_sample - Get sample rows from a table (default: 10, max: 100)
get_relationships - Get foreign key relationships between tables
get_connection_status - Test connection and get database version info

Connection String Format

PostgreSQL connection strings support multiple formats:

# Basic
"host=localhost user=postgres dbname=mydb"

# With password
"host=localhost user=postgres dbname=mydb password=secret"

# With port
"host=localhost port=5433 user=postgres dbname=mydb"

# Full URL format
"postgresql://postgres:secret@localhost:5432/mydb"

See the tokio-postgres documentation for all connection options.

Examples

Query data

{
  "query": "SELECT * FROM users WHERE active = true LIMIT 10"
}

Insert data

{
  "table_name": "users",
  "data": {
    "username": "alice",
    "email": "alice@example.com",
    "active": true
  }
}

Update data

{
  "table_name": "users",
  "values": {
    "active": false
  },
  "where_conditions": {
    "username": "alice"
  }
}

Get schema for a table

{
  "table_name": "users"
}

Safety Features

Update and delete operations have default limits (1000 rows)
WHERE conditions required for updates and deletes
Raw query execution requires explicit tool call
Connection string passwords are sanitized in logs

Development

# Build
cargo build

# Run tests
cargo test

# Run with debug logging
RUST_LOG=rmcp_postgres=debug,rmcp=debug rmcp-postgres

Contributing

Contributions welcome! Please feel free to submit issues or pull requests.

License

MIT

Related Projects

rmcp - Rust MCP SDK
Model Context Protocol - The MCP specification

rmcp-postgres 0.1.0