ClickHouse MCP Server

An MCP server for ClickHouse.

Features

Tools

run_select_query
- Execute SQL queries on your ClickHouse cluster.
- Input: sql (string): The SQL query to execute.
- All ClickHouse queries are run with readonly = 1 to ensure they are safe.
list_databases
- List all databases on your ClickHouse cluster.
list_tables
- List all tables in a database.
- Input: database (string): The name of the database.

Configuration

Open the Claude Desktop configuration file located at:
- On macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
- On Windows: %APPDATA%/Claude/claude_desktop_config.json
Add the following:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.13",
        "mcp-clickhouse"
      ],
      "env": {
        "CLICKHOUSE_HOST": "<clickhouse-host>",
        "CLICKHOUSE_PORT": "<clickhouse-port>",
        "CLICKHOUSE_USER": "<clickhouse-user>",
        "CLICKHOUSE_PASSWORD": "<clickhouse-password>",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT": "30",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT": "30"
      }
    }
  }
}

Update the environment variables to point to your own ClickHouse service.

Or, if you'd like to try it out with the ClickHouse SQL Playground, you can use the following config:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.13",
        "mcp-clickhouse"
      ],
      "env": {
        "CLICKHOUSE_HOST": "sql-clickhouse.clickhouse.com",
        "CLICKHOUSE_PORT": "8443",
        "CLICKHOUSE_USER": "demo",
        "CLICKHOUSE_PASSWORD": "",
        "CLICKHOUSE_SECURE": "true",
        "CLICKHOUSE_VERIFY": "true",
        "CLICKHOUSE_CONNECT_TIMEOUT": "30",
        "CLICKHOUSE_SEND_RECEIVE_TIMEOUT": "30"
      }
    }
  }
}

Locate the command entry for uv and replace it with the absolute path to the uv executable. This ensures that the correct version of uv is used when starting the server. On a mac, you can find this path using which uv.
Restart Claude Desktop to apply the changes.

Development

In test-services directory run docker compose up -d to start the ClickHouse cluster.
Add the following variables to a .env file in the root of the repository.

CLICKHOUSE_HOST=localhost
CLICKHOUSE_PORT=8123
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=clickhouse

Run uv sync to install the dependencies. To install uv follow the instructions here. Then do source .venv/bin/activate.
For easy testing, you can run fastmcp dev mcp_clickhouse/mcp_server.py to start the MCP server.

Environment Variables

The following environment variables are used to configure the ClickHouse connection:

Required Variables

CLICKHOUSE_HOST: The hostname of your ClickHouse server
CLICKHOUSE_USER: The username for authentication
CLICKHOUSE_PASSWORD: The password for authentication

Optional Variables

CLICKHOUSE_PORT: The port number of your ClickHouse server
- Default: 8443 if HTTPS is enabled, 8123 if disabled
- Usually doesn't need to be set unless using a non-standard port
CLICKHOUSE_SECURE: Enable/disable HTTPS connection
- Default: "true"
- Set to "false" for non-secure connections
CLICKHOUSE_VERIFY: Enable/disable SSL certificate verification
- Default: "true"
- Set to "false" to disable certificate verification (not recommended for production)
CLICKHOUSE_CONNECT_TIMEOUT: Connection timeout in seconds
- Default: "30"
- Increase this value if you experience connection timeouts
CLICKHOUSE_SEND_RECEIVE_TIMEOUT: Send/receive timeout in seconds
- Default: "300"
- Increase this value for long-running queries
CLICKHOUSE_DATABASE: Default database to use
- Default: None (uses server default)
- Set this to automatically connect to a specific database

Example Configurations

For local development with Docker:

# Required variables
CLICKHOUSE_HOST=localhost
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=clickhouse

# Optional: Override defaults for local development
CLICKHOUSE_SECURE=false  # Uses port 8123 automatically
CLICKHOUSE_VERIFY=false

For ClickHouse Cloud:

# Required variables
CLICKHOUSE_HOST=your-instance.clickhouse.cloud
CLICKHOUSE_USER=default
CLICKHOUSE_PASSWORD=your-password

# Optional: These use secure defaults
# CLICKHOUSE_SECURE=true  # Uses port 8443 automatically
# CLICKHOUSE_DATABASE=your_database

For ClickHouse SQL Playground:

CLICKHOUSE_HOST=sql-clickhouse.clickhouse.com
CLICKHOUSE_USER=demo
CLICKHOUSE_PASSWORD=
# Uses secure defaults (HTTPS on port 8443)

You can set these variables in your environment, in a .env file, or in the Claude Desktop configuration:

{
  "mcpServers": {
    "mcp-clickhouse": {
      "command": "uv",
      "args": [
        "run",
        "--with",
        "mcp-clickhouse",
        "--python",
        "3.13",
        "mcp-clickhouse"
      ],
      "env": {
        "CLICKHOUSE_HOST": "<clickhouse-host>",
        "CLICKHOUSE_USER": "<clickhouse-user>",
        "CLICKHOUSE_PASSWORD": "<clickhouse-password>",
        "CLICKHOUSE_DATABASE": "<optional-database>"
      }
    }
  }
}