MCP Image Placeholder Server

Instructions

Generate a placeholder image based on a provider, width, and height.
Use this tool to generate a placeholder image for testing or development purposes.

Args:
    provider: The provider to use for the image, must be either `placehold` or `lorem-picsum`.
    width: The width of the image, must be a positive integer between 1 and 10000.
    height: The height of the image, must be a positive integer between 1 and 10000.

Implementation Reference

• main.py:8-52 (handler)

  The core handler function for the 'image_placeholder' tool. It validates inputs and generates a URL to a placeholder image from either 'placehold.co' or 'picsum.photos' based on the provider, decorated with @mcp.tool() for registration.

  @mcp.tool()
  def image_placeholder(
      provider: Literal["placehold", "lorem-picsum"],
      width: int,
      height: int,
  ) -> str:
      """
      Generate a placeholder image based on a provider, width, and height.
      Use this tool to generate a placeholder image for testing or development purposes.
  
      Args:
          provider: The provider to use for the image, must be either `placehold` or `lorem-picsum`.
          width: The width of the image, must be a positive integer between 1 and 10000.
          height: The height of the image, must be a positive integer between 1 and 10000.
      """
      # if provider is not in the list of providers, raise a ValueError
      if provider not in ["placehold", "lorem-picsum"]:
          raise ValueError(f"Invalid provider: {provider}")
  
      # if width is not a positive integer between 1 and 10000, raise a ValueError
      if width <= 0 or width > 10000:
          raise ValueError(
              f"Invalid width: {width}. Width must be a positive integer between 1 and 10000"
          )
  
      # if height is not a positive integer between 1 and 10000, raise a ValueError
      if height <= 0 or height > 10000:
          raise ValueError(
              f"Invalid height: {height}. Height must be a positive integer between 1 and 10000"
          )
  
      # if provider is placehold, return the placehold image
      if provider == "placehold":
          return (
              f"https://placehold.co/{width}x{height}"
              if height is not None
              else f"https://placehold.co/{width}"
          )
      # if provider is lorem-picsum, return the lorem-picsum image
      elif provider == "lorem-picsum":
          return (
              f"https://picsum.photos/{width}/{height}"
              if height is not None
              else f"https://picsum.photos/{width}"
          )

• main.py:9-22 (schema)

  Input schema defined by function parameters and docstring: provider (enum: 'placehold' or 'lorem-picsum'), width/height (positive ints 1-10000), returns string URL.

  def image_placeholder(
      provider: Literal["placehold", "lorem-picsum"],
      width: int,
      height: int,
  ) -> str:
      """
      Generate a placeholder image based on a provider, width, and height.
      Use this tool to generate a placeholder image for testing or development purposes.
  
      Args:
          provider: The provider to use for the image, must be either `placehold` or `lorem-picsum`.
          width: The width of the image, must be a positive integer between 1 and 10000.
          height: The height of the image, must be a positive integer between 1 and 10000.
      """

• main.py:5-5 (registration)

  Initializes the FastMCP server instance named 'image-placeholder', to which tools are registered.

  mcp = FastMCP("image-placeholder")