Find foods in the USDA FoodData Central database by free-text name. Use this FIRST when the user mentions a food by name and you need its fdc_id for any of the other nutrition_* tools. Returns ranked matches with fdc_id, description, brand_owner, and a quick macro summary (calories/protein/carbs/fat per 100g). Charges $0.001 USDC per call.

Args: q: Free-text food name (e.g. "banana", "greek yogurt", "chicken breast"). limit: Max results to return, 1-50. Default 10. Use a small limit unless you need to browse.

Get the full per-100g nutrition profile for one specific food. Use this when you have an fdc_id (from nutrition_search) and the user needs micronutrients beyond just calories/protein/carbs/fat. Returns all 13 tracked nutrients: calories, protein, fat, carbs, fiber, sugar, sodium, cholesterol, saturated_fat, vitamin_c, calcium, iron, potassium. Missing nutrients are null, not 0. Charges $0.002 USDC per call.

Args: fdc_id: USDA FoodData Central ID, obtained from nutrition_search.

Compare 2 to 5 foods side by side. Use this when the user asks "which is healthier," "which has more protein," or any cross-food comparison — it's cheaper and clearer than calling nutrition_detail multiple times. Returns each food's full nutrition plus per-nutrient winners (highest protein, lowest sodium, etc.). Charges $0.003 USDC per call.

Args: fdc_ids: 2 to 5 USDA FDC IDs to compare.

Sum nutrition across a recipe of weighted ingredients. Use this for meal planning, recipe analysis, or any "what are the totals if I combine X grams of A with Y grams of B" task. Each food's per-100g nutrition is scaled by grams/100 then summed. Charges $0.005 USDC per call.

Args: ingredients: List of {"fdc_id": int, "grams": float} pairs. At least one; weights in grams.