Postgres MCP Pro

Instructions

Implementation Reference

• src/postgres_mcp/server.py:390-402 (handler)

  The implementation of the `execute_sql` tool which executes SQL against the database driver.

  async def execute_sql(
      sql: str = Field(description="SQL to run", default="all"),
  ) -> ResponseType:
      """Executes a SQL query against the database."""
      try:
          sql_driver = await get_sql_driver()
          rows = await sql_driver.execute_query(sql)  # type: ignore
          if rows is None:
              return format_text_response("No results")
          return format_text_response(list([r.cells for r in rows]))
      except Exception as e:
          logger.error(f"Error executing query: {e}")
          return format_error_response(str(e))

• src/postgres_mcp/server.py:550-553 (registration)

  Registration of the `execute_sql` tool within the MCP server, with different descriptions depending on the access mode.

  if current_access_mode == AccessMode.UNRESTRICTED:
      mcp.add_tool(execute_sql, description="Execute any SQL query")
  else:
      mcp.add_tool(execute_sql, description="Execute a read-only SQL query")