USQL MCP Server

usql-mcp bridges the Model Context Protocol with the usql CLI so assistants and other MCP clients can run queries against any database usql supports. The server forwards tool requests directly to usql and streams the raw CLI output back to the caller (JSON by default, CSV on request), keeping behaviour identical to what you would see on the command line.

Requirements

• Node.js 16 or newer
• npm
• usql installed and available on PATH

Quick Launch with npx

Run the server directly via npx:

npx usql-mcp

This downloads the package and executes the CLI entry point, which runs the MCP server on stdio.

You can also run it directly from the repository using npm's Git support (the prepare script compiles the TypeScript automatically):

npx github:jvm/usql-mcp

Getting Started

git clone https://github.com/yourusername/usql-mcp.git
cd usql-mcp
npm install
npm run build

The compiled files live in dist/. They are intentionally not committed—run npm run build whenever you need fresh output.

Configuring Connections

Define connection strings via environment variables (USQL_*) or a config.json file mirroring config.example.json. Each USQL_<NAME>=... entry becomes a reusable connection whose name is the lower-cased <name> portion (USQL_ORACLE1 → oracle1). Reserved keys that aren’t treated as connections are:

• USQL_CONFIG_PATH
• USQL_QUERY_TIMEOUT_MS
• USQL_DEFAULT_CONNECTION
• USQL_BINARY_PATH

Examples:

export USQL_POSTGRES="postgres://user:password@localhost:5432/mydb"
export USQL_SQLITE="sqlite:///$(pwd)/data/app.db"
export USQL_ORACLE1="oracle://user:secret@host1:1521/service"
export USQL_ORACLE2="oracle://user:secret@host2:1521/service"

You can also supply a full URI directly in tool requests. USQL_QUERY_TIMEOUT_MS controls the default query timeout; leave it unset (or set defaults.queryTimeout to null) for unlimited execution and override it when you need a guard. Individual tool calls can pass timeout_ms to override (set to null for unlimited on that call). Set USQL_DEFAULT_CONNECTION (or defaults.defaultConnection in config.json) to name the connection that should be used automatically when a tool call omits the connection_string field.

If usql is not on your PATH, set USQL_BINARY_PATH to the absolute path of the executable (for example, /usr/local/bin/usql). When unset, the MCP server assumes usql is discoverable via the environment PATH.

Client Configuration

This section explains how to configure the usql-mcp server in different MCP clients.

Claude Desktop

Claude Desktop uses a configuration file to register MCP servers. The location depends on your operating system:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

Add the following configuration to your claude_desktop_config.json:

{
  "mcpServers": {
    "usql": {
      "command": "npx",
      "args": ["usql-mcp"],
      "env": {
        "USQL_POSTGRES": "postgres://user:password@localhost:5432/mydb",
        "USQL_SQLITE": "sqlite:///path/to/database.db",
        "USQL_DEFAULT_CONNECTION": "postgres",
        "USQL_QUERY_TIMEOUT_MS": "30000"
      }
    }
  }
}

After editing the configuration file, restart Claude Desktop for changes to take effect.

Claude Code

Claude Code (CLI) supports MCP servers through its configuration file located at:

• All platforms: ~/.clauderc or ~/.config/claude/config.json

Add the MCP server to your Claude Code configuration:

{
  "mcpServers": {
    "usql": {
      "command": "npx",
      "args": ["-y", "usql-mcp"],
      "env": {
        "USQL_POSTGRES": "postgres://user:password@localhost:5432/mydb",
        "USQL_DEFAULT_CONNECTION": "postgres"
      }
    }
  }
}

The server will be available in your Claude Code sessions automatically.

Codex CLI

Codex CLI configuration varies by implementation, but typically uses a similar JSON configuration approach. Create or edit your Codex configuration file (usually ~/.codexrc or as specified in your Codex documentation):

{
  "mcp": {
    "servers": {
      "usql": {
        "command": "npx",
        "args": ["-y", "usql-mcp"],
        "env": {
          "USQL_POSTGRES": "postgres://user:password@localhost:5432/mydb",
          "USQL_MYSQL": "mysql://user:password@localhost:3306/mydb"
        }
      }
    }
  }
}

Refer to your specific Codex CLI documentation for the exact configuration file location and format.

GitHub Copilot (VS Code)

GitHub Copilot in VS Code can use MCP servers through the Copilot Chat extension settings. Configuration is done through VS Code's settings.json:

1. Open VS Code Settings (JSON) via:

   • macOS: Cmd + Shift + P → "Preferences: Open User Settings (JSON)"
   • Windows/Linux: Ctrl + Shift + P → "Preferences: Open User Settings (JSON)"

2. Add the MCP server configuration:

{
  "github.copilot.chat.mcp.servers": {
    "usql": {
      "command": "npx",
      "args": ["-y", "usql-mcp"],
      "env": {
        "USQL_POSTGRES": "postgres://user:password@localhost:5432/mydb",
        "USQL_SQLITE": "sqlite:///absolute/path/to/database.db",
        "USQL_DEFAULT_CONNECTION": "postgres"
      }
    }
  }
}

After saving the settings, reload VS Code or restart the Copilot extension for changes to take effect.

Environment Variables vs. Configuration

For all clients, you can choose between:

1. Inline environment variables (shown above) - Connection strings in the config file
2. System environment variables - Set USQL_* variables in your shell profile

System environment approach:

# In ~/.bashrc, ~/.zshrc, or equivalent
export USQL_POSTGRES="postgres://user:password@localhost:5432/mydb"
export USQL_SQLITE="sqlite:///path/to/database.db"
export USQL_DEFAULT_CONNECTION="postgres"

Then use a simpler client configuration:

{
  "mcpServers": {
    "usql": {
      "command": "npx",
      "args": ["-y", "usql-mcp"]
    }
  }
}

Security Best Practices

• Avoid hardcoding credentials: Use environment variables or secure credential stores
• File permissions: Ensure configuration files with credentials are not world-readable (chmod 600)
• Read-only access: Create database users with minimal required permissions for AI queries
• Network security: Use SSL/TLS connections for remote databases
• Audit logging: Enable database audit logs to track AI-generated queries

Tool Catalogue

Tool	Purpose	Notable Inputs
execute_query	Run an arbitrary SQL statement	connection_string, query, optional output_format (json|csv), timeout_ms
execute_script	Execute a multi-statement script	connection_string, script, optional output_format, timeout_ms
list_databases	List databases available on the server	connection_string, optional output_format, timeout_ms
list_tables	List tables in the current database	connection_string, optional output_format, timeout_ms
describe_table	Inspect table metadata via \d	connection_string, table, optional output_format, timeout_ms

Successful calls return the exact stdout produced by usql, paired with the format indicator:

{
  "format": "json", // or "csv"
  "content": "[{\"id\":1}]"
}

If usql exits with a non-zero code the handler forwards the message through the MCP error shape, keeping details like the sanitized connection string and original stderr.

Development

• npm run dev – TypeScript compile in watch mode
• npm run build – emit ESM output to dist/
• npm run lint – ESLint/Prettier rules
• npm run test – Jest unit tests (no external services required)
• npm run type-check – strict tsc --noEmit

Debug logging follows the namespace in DEBUG=usql-mcp:*.

Contributing

See AGENTS.md for contributor guidelines. Open an issue before large changes so we can keep the tooling lean and aligned with the MCP ecosystem.