MCP Vertica

Instructions

Implementation Reference

• src/mcp_vertica/mcp.py:367-458 (handler)

  The main handler function for the 'get_table_structure' tool. It is decorated with @mcp.tool(), which serves as both the implementation and registration with the FastMCP server. The function connects to Vertica, queries v_catalog.columns for column info and v_catalog.constraint_columns for constraints, then formats and returns the table structure as a string.
  @mcp.tool() async def get_table_structure( ctx: Context, table_name: str, schema: str = "public" ) -> str: """Get the structure of a table including columns, data types, and constraints. Args: ctx: FastMCP context for progress reporting and logging table_name: Name of the table to inspect schema: Schema name (default: public) Returns: Table structure information as a string """ await ctx.info(f"Getting structure for table: {schema}.{table_name}") # Get or create connection manager manager = await get_or_create_manager(ctx) if not manager: return "Error: Failed to initialize database connection. Check configuration." query = """ SELECT column_name, data_type, character_maximum_length, numeric_precision, numeric_scale, is_nullable, column_default FROM v_catalog.columns WHERE table_schema = %s AND table_name = %s ORDER BY ordinal_position; """ conn = None cursor = None try: conn = manager.get_connection() cursor = conn.cursor() cursor.execute(query, (schema, table_name)) columns = cursor.fetchall() if not columns: return f"No table found: {schema}.{table_name}" # Get constraints cursor.execute(""" SELECT constraint_name, constraint_type, column_name FROM v_catalog.constraint_columns WHERE table_schema = %s AND table_name = %s; """, (schema, table_name)) constraints = cursor.fetchall() # Format the output result = f"Table Structure for {schema}.{table_name}:\n\n" result += "Columns:\n" for col in columns: result += f"- {col[0]}: {col[1]}" if col[2]: # character_maximum_length result += f"({col[2]})" elif col[3]: # numeric_precision result += f"({col[3]},{col[4]})" result += f" {'NULL' if col[5] == 'YES' else 'NOT NULL'}" if col[6]: # column_default result += f" DEFAULT {col[6]}" result += "\n" if constraints: result += "\nConstraints:\n" for const in constraints: result += f"- {const[0]} ({const[1]}): {const[2]}\n" return result except Exception as e: error_msg = f"Error getting table structure: {str(e)}" await ctx.error(error_msg) return error_msg finally: if cursor: cursor.close() if conn: manager.release_connection(conn)