fix: add retry with exponential backoff to weather MCP tool

mcp/weather_tool/weather_tool.py

@@ -4,9 +4,12 @@
 import logging
 import os
 import sys
+import time
 
 import requests
 from fastmcp import FastMCP
+from requests.adapters import HTTPAdapter
+from urllib3.util.retry import Retry
 
 mcp = FastMCP("Weather")
 logger = logging.getLogger(__name__)
@@ -16,29 +19,67 @@
     format="%(levelname)s: %(message)s",
 )
 
+# Configurable timeouts and retries for external API resilience
+_REQUEST_TIMEOUT = int(os.getenv("WEATHER_REQUEST_TIMEOUT", "30"))
+_MAX_RETRIES = int(os.getenv("WEATHER_MAX_RETRIES", "3"))
+_BACKOFF_FACTOR = float(os.getenv("WEATHER_BACKOFF_FACTOR", "1.0"))
+
+
+def _resilient_session() -> requests.Session:
+    """Create an HTTP session with automatic retry and exponential backoff."""
+    session = requests.Session()
+    retry_strategy = Retry(
+        total=_MAX_RETRIES,
+        backoff_factor=_BACKOFF_FACTOR,
+        status_forcelist=[429, 500, 502, 503, 504],
+        allowed_methods=["GET"],
+        raise_on_status=False,
+    )
+    adapter = HTTPAdapter(max_retries=retry_strategy)
+    session.mount("https://", adapter)
+    session.mount("http://", adapter)
+    return session
+
 
 @mcp.tool(annotations={"readOnlyHint": True, "destructiveHint": False, "idempotentHint": True})
 def get_weather(city: str) -> str:
     """Get weather info for a city"""
     logger.debug(f"Getting weather info for city '{city}'.")
+    session = _resilient_session()
+
+    # Geocoding: resolve city name to coordinates
     base_url = "https://geocoding-api.open-meteo.com/v1/search"
     params = {"name": city, "count": 1}
-    response = requests.get(base_url, params=params, timeout=10)
-    data = response.json()
+    try:
+        response = session.get(base_url, params=params, timeout=_REQUEST_TIMEOUT)
+        response.raise_for_status()
+        data = response.json()
+    except (requests.RequestException, ValueError) as exc:
+        logger.warning("Geocoding API error for '%s': %s", city, exc)
+        return f"Weather service temporarily unavailable for {city} (geocoding error)"
+
     if not data or "results" not in data:
         return f"City {city} not found"
     latitude = data["results"][0]["latitude"]
     longitude = data["results"][0]["longitude"]
 
+    # Forecast: get current weather at coordinates
     weather_url = "https://api.open-meteo.com/v1/forecast"
     weather_params = {
         "latitude": latitude,
         "longitude": longitude,
         "temperature_unit": "fahrenheit",
         "current_weather": True,
     }
-    weather_response = requests.get(weather_url, params=weather_params, timeout=10)
-    weather_data = weather_response.json()
+    try:
+        weather_response = session.get(
+            weather_url, params=weather_params, timeout=_REQUEST_TIMEOUT
+        )
+        weather_response.raise_for_status()
+        weather_data = weather_response.json()
+    except (requests.RequestException, ValueError) as exc:
+        logger.warning("Forecast API error for '%s': %s", city, exc)
+        return f"Weather service temporarily unavailable for {city} (forecast error)"
 
     return json.dumps(weather_data["current_weather"])