Prefect MCP Server

Instructions

Implementation Reference

• src/mcp_prefect/variable.py:75-108 (handler)

  The main handler function for the 'create_variable' MCP tool. It is decorated with @mcp.tool, which handles both registration and schema inference from the type hints and docstring. The function creates a Prefect variable using the Prefect client and returns the result as MCP TextContent.

  @mcp.tool
  async def create_variable(
      name: str,
      value: Any,
      tags: Optional[List[str]] = None,
  ) -> List[Union[types.TextContent, types.ImageContent, types.EmbeddedResource]]:
      """
      Create a variable.
      
      Args:
          name: The variable name
          value: The variable value (can be string, dict, list, etc.)
          tags: Optional tags
          
      Returns:
          Details of the created variable or error message
      """
      try:
          async with get_client() as client:
              from prefect.client.schemas.actions import VariableCreate
              
              # Create the proper variable object
              variable_create = VariableCreate(
                  name=name,
                  value=value,
                  tags=tags or []
              )
              
              variable = await client.create_variable(variable=variable_create)
              
              variable_result = {"variable": variable.model_dump()}
              return [types.TextContent(type="text", text=json.dumps(variable_result, indent=2, default=str))]
      except Exception as e:
          return [types.TextContent(type="text", text=json.dumps({"error": str(e)}, indent=2))]