mcp-clickhouse

Instructions

Implementation Reference

• mcp_clickhouse/mcp_server.py:124-138 (handler)

  The main handler function for the 'list_databases' tool. It connects to ClickHouse, runs 'SHOW DATABASES', processes the result into a list of database names, and returns them as a JSON string.

  def list_databases():
      """List available ClickHouse databases"""
      logger.info("Listing all databases")
      client = create_clickhouse_client()
      result = client.command("SHOW DATABASES")
  
      # Convert newline-separated string to list and trim whitespace
      if isinstance(result, str):
          databases = [db.strip() for db in result.strip().split("\n")]
      else:
          databases = [result]
  
      logger.info(f"Found {len(databases)} databases")
      return json.dumps(databases)

• mcp_clickhouse/mcp_server.py:562-567 (registration)

  Registers the 'list_databases' tool (along with others) with the FastMCP server instance if ClickHouse is enabled via environment variable.

  if os.getenv("CLICKHOUSE_ENABLED", "true").lower() == "true":
      mcp.add_tool(Tool.from_function(list_databases))
      mcp.add_tool(Tool.from_function(list_tables))
      mcp.add_tool(Tool.from_function(run_select_query))
      logger.info("ClickHouse tools registered")

• mcp_clickhouse/__init__.py:5-26 (registration)

  Exposes the list_databases function in the package __init__ for easy import.

      list_databases,
      list_tables,
      run_select_query,
      create_chdb_client,
      run_chdb_select_query,
      chdb_initial_prompt,
      table_pagination_cache,
      fetch_table_names_from_system,
      get_paginated_table_data,
      create_page_token,
  )
  
  
  if os.getenv("MCP_CLICKHOUSE_TRUSTSTORE_DISABLE", None) != "1":
      try:
          import truststore
          truststore.inject_into_ssl()
      except Exception:
          pass
  
  __all__ = [
      "list_databases",