mcp_fetch

Instructions

Implementation Reference

• mcp_simple_tool/server.py:8-39 (handler)

  Core handler function that implements the logic for the 'mcp_fetch' tool: fetches website content using httpx, follows redirects, handles timeouts, HTTP errors, and other exceptions, returning formatted TextContent.

  async def fetch_website(
      url: str,
  ) -> list[types.TextContent | types.ImageContent | types.EmbeddedResource]:
      headers = {
          "User-Agent": "MCP Test Server (github.com/modelcontextprotocol/python-sdk)"
      }
      try:
          timeout = httpx.Timeout(10.0, connect=5.0)
          async with httpx.AsyncClient(
              follow_redirects=True, 
              headers=headers,
              timeout=timeout
          ) as client:
              response = await client.get(url)
              response.raise_for_status()
              return [types.TextContent(type="text", text=response.text)]
      except httpx.TimeoutException:
          return [types.TextContent(
              type="text",
              text="Error: Request timed out while trying to fetch the website."
          )]
      except httpx.HTTPStatusError as e:
          return [types.TextContent(
              type="text",
              text=(f"Error: HTTP {e.response.status_code} "
                    "error while fetching the website.")
          )]
      except Exception as e:
          return [types.TextContent(
              type="text",
              text=f"Error: Failed to fetch website: {str(e)}"
          )]

• mcp_simple_tool/server.py:95-108 (registration)

  Registration of the 'mcp_fetch' tool in the list_tools() function, including name, description, and input schema.

  types.Tool(
      name="mcp_fetch",
      description="Fetches a website and returns its content",
      inputSchema={
          "type": "object",
          "required": ["url"],
          "properties": {
              "url": {
                  "type": "string",
                  "description": "URL to fetch",
              }
          },
      },
  ),

• mcp_simple_tool/server.py:98-107 (schema)

  Input schema definition for the 'mcp_fetch' tool, specifying an object with a required 'url' string property.

  inputSchema={
      "type": "object",
      "required": ["url"],
      "properties": {
          "url": {
              "type": "string",
              "description": "URL to fetch",
          }
      },
  },

• mcp_simple_tool/server.py:72-78 (handler)

  Dispatch logic within the general call_tool handler that routes 'mcp_fetch' calls to the fetch_website function after validating the 'url' argument.

  if name == "mcp_fetch":
      if "url" not in arguments:
          return [types.TextContent(
              type="text",
              text="Error: Missing required argument 'url'"
          )]
      return await fetch_website(arguments["url"])

• mcp_simple_tool/server.py:68-91 (handler)

  The @app.call_tool()-decorated handler function that implements dispatching for all tools, including 'mcp_fetch'.

  @app.call_tool()
  async def fetch_tool( # type: ignore[unused-function]
      name: str, arguments: dict
  ) -> list[types.TextContent | types.ImageContent | types.EmbeddedResource]:
      if name == "mcp_fetch":
          if "url" not in arguments:
              return [types.TextContent(
                  type="text",
                  text="Error: Missing required argument 'url'"
              )]
          return await fetch_website(arguments["url"])
      elif name == "mood":
          if "question" not in arguments:
              return [types.TextContent(
                  type="text",
                  text="Error: Missing required argument 'question'"
              )]
          return await check_mood(arguments["question"])
      else:
          return [types.TextContent(
              type="text",
              text=f"Error: Unknown tool: {name}"
          )]