Slim MCP

Instructions

Implementation Reference

• src/claude_tools/weather.py:33-42 (handler)

  The main handler function for the 'get_alerts' tool. It fetches active weather alerts for a given US state from the National Weather Service API, processes the response, formats each alert using the 'format_alert' helper, and returns a concatenated string of formatted alerts.

  async def get_alerts(state: str) -> str:
      """Get weather alerts for a US state."""
      url = f"{NWS_API_BASE}/alerts/active/area/{state}"
      data = await make_nws_request(url)
      if not data or "features" not in data:
          return "Unable to fetch alerts or no alerts found."
      if not data["features"]:
          return "No active alerts for this state."
      alerts = [format_alert(feature) for feature in data["features"]]
      return "\n---\n".join(alerts)

• src/claude_tools/weather.py:71-75 (registration)

  Registers the 'get_alerts' tool (along with 'get_forecast') using the MCP 'mcp.tool()' decorator within the register_weather_tools function.

  def register_weather_tools(mcp):
      """Register all weather tools with the MCP server."""
      mcp.tool()(get_alerts)
      mcp.tool()(get_forecast)

• src/claude_tools/weather.py:22-31 (helper)

  Helper function specifically used by 'get_alerts' to format individual alert features from the API response into a human-readable multi-line string.

  def format_alert(feature: dict) -> str:
      """Format an alert feature into a readable string."""
      props = feature["properties"]
      return f"""
  Event: {props.get('event', 'Unknown')}
  Area: {props.get('areaDesc', 'Unknown')}
  Severity: {props.get('severity', 'Unknown')}
  Description: {props.get('description', 'No description available')}
  Instructions: {props.get('instruction', 'No specific instructions provided')}
  """

• src/claude_tools/weather.py:8-20 (helper)

  Shared helper function used by 'get_alerts' (and 'get_forecast') to make asynchronous HTTP requests to the National Weather Service API with proper headers, timeout, and error handling.

  async def make_nws_request(url: str) -> dict[str, Any] | None:
      """Make a request to the NWS API with proper error handling."""
      headers = {
          "User-Agent": USER_AGENT,
          "Accept": "application/geo+json"
      }
      async with httpx.AsyncClient() as client:
          try:
              response = await client.get(url, headers=headers, timeout=30.0)
              response.raise_for_status()
              return response.json()
          except Exception:
              return None