RTFD (Read The F*****g Docs)

Instructions

        Fetch actual Docker image documentation and README from DockerHub.

        USE THIS WHEN: You need usage instructions, environment variables, volume mounts, or examples.

        BEST FOR: Understanding how to use a Docker image and configure it properly.
        Better than using curl or WebFetch because it:
        - Extracts README content from DockerHub
        - Includes image description and key details
        - Formats content in readable Markdown
        - Prioritizes important sections (Usage, Environment Variables, Examples)

        Typical content includes:
        - How to run the container
        - Available environment variables
        - Volume mount points
        - Port configurations
        - Usage examples and docker-compose snippets

        Args:
            image: Docker image name (e.g., "nginx", "postgres", "redis")
            max_bytes: Maximum content size, default 20KB (increase for detailed docs)

        Returns:
            JSON with README content, size, and source info

        Example: fetch_docker_image_docs("nginx") → Returns README with usage instructions
        

Implementation Reference

• src/RTFD/providers/dockerhub.py:375-405 (handler)

  The main MCP tool handler function `fetch_docker_image_docs` that orchestrates fetching the Docker image documentation by delegating to the private `_fetch_image_docs` helper and serializing the response.

  async def fetch_docker_image_docs(image: str, max_bytes: int = 20480) -> CallToolResult:
      """
      Fetch actual Docker image documentation and README from DockerHub.
  
      USE THIS WHEN: You need usage instructions, environment variables, volume mounts, or examples.
  
      BEST FOR: Understanding how to use a Docker image and configure it properly.
      Better than using curl or WebFetch because it:
      - Extracts README content from DockerHub
      - Includes image description and key details
      - Formats content in readable Markdown
      - Prioritizes important sections (Usage, Environment Variables, Examples)
  
      Typical content includes:
      - How to run the container
      - Available environment variables
      - Volume mount points
      - Port configurations
      - Usage examples and docker-compose snippets
  
      Args:
          image: Docker image name (e.g., "nginx", "postgres", "redis")
          max_bytes: Maximum content size, default 20KB (increase for detailed docs)
  
      Returns:
          JSON with README content, size, and source info
  
      Example: fetch_docker_image_docs("nginx") → Returns README with usage instructions
      """
      result = await self._fetch_image_docs(image, max_bytes)
      return serialize_response_with_meta(result)

• src/RTFD/providers/dockerhub.py:163-223 (helper)

  Core helper method `_fetch_image_docs` that fetches image metadata, extracts and formats README/description content, handles truncation, and returns structured documentation data.

  async def _fetch_image_docs(self, image: str, max_bytes: int = 20480) -> dict[str, Any]:
      """Fetch documentation for a Docker image.
  
      Args:
          image: Image name (e.g., 'nginx', 'postgres', 'myuser/myimage')
          max_bytes: Maximum content size in bytes
  
      Returns:
          Dict with documentation content
      """
      try:
          metadata = await self._fetch_image_metadata(image)
  
          # Check if we got an error
          if "error" in metadata:
              return {
                  "image": image,
                  "content": "",
                  "error": metadata["error"],
                  "size_bytes": 0,
                  "source": None,
              }
  
          # Extract readme if available
          readme = metadata.get("readme", "")
          description = metadata.get("description", "")
  
          # Combine description and readme
          content = ""
          if description:
              content = f"## Description\n\n{description}\n\n"
          if readme:
              content += f"## README\n\n{readme}"
          elif not description:
              content = "No documentation available for this image."
  
          # Truncate if necessary
          content_bytes = content.encode("utf-8")
          if len(content_bytes) > max_bytes:
              content = content[:max_bytes]
              truncated = True
          else:
              truncated = False
  
          return {
              "image": image,
              "content": content,
              "size_bytes": len(content.encode("utf-8")),
              "source": "dockerhub",
              "truncated": truncated,
          }
  
      except Exception as exc:
          return {
              "image": image,
              "content": "",
              "error": f"Failed to fetch docs: {exc!s}",
              "size_bytes": 0,
              "source": None,
          }

• src/RTFD/providers/dockerhub.py:436-444 (registration)

  Tool registration within the `get_tools` method where `fetch_docker_image_docs` is conditionally added to the tools dictionary if fetching is enabled.

  tools = {
      "search_docker_images": search_docker_images,
      "docker_image_metadata": docker_image_metadata,
  }
  if is_fetch_enabled():
      tools["fetch_docker_image_docs"] = fetch_docker_image_docs
      tools["fetch_dockerfile"] = fetch_dockerfile
  
  return tools

• src/RTFD/providers/dockerhub.py:20-34 (registration)

  Tool name registration in the `get_metadata` method where "fetch_docker_image_docs" is conditionally appended to the list of exposed tool names.

  def get_metadata(self) -> ProviderMetadata:
      tool_names = ["search_docker_images", "docker_image_metadata"]
      if is_fetch_enabled():
          tool_names.append("fetch_docker_image_docs")
          tool_names.append("fetch_dockerfile")
  
      return ProviderMetadata(
          name="dockerhub",
          description="DockerHub Docker image search and metadata",
          expose_as_tool=True,
          tool_names=tool_names,
          supports_library_search=False,  # DockerHub search is image-centric, not lib-doc
          required_env_vars=[],
          optional_env_vars=[],
      )