USDA FoodData Central API Skill

This skill provides access to the USDA FoodData Central API for searching foods and retrieving detailed nutritional information.

Important Limitations

Language: All food descriptions and search queries must be in English. The database does not support searching in other languages.

Geographic Scope: This is a US-focused database. The "Branded" data type contains primarily US commercial food products. While "Foundation" and "SR Legacy" include generic foods (like "apples, raw" or "chicken, grilled"), brand-specific items will be American brands. European or other international brands will generally not be found.

Prerequisites

The skill requires a valid FDC API key to function. The key should be available via the FDC_API_KEY environment variable.

Getting an API Key

If FDC_API_KEY is not set, guide the user through this onboarding process:

1. Navigate to: https://fdc.nal.usda.gov/api-key-signup
2. Fill out the form with these required fields:
   • First Name
   • Last Name
   • Email
3. Submit the form and check your email for the 40-character API key
4. Add the key to OpenClaw configuration:
   • Edit ~/.openclaw/openclaw.json
   • Add the API key to the environment variables section:

     {
       "env": {
         "FDC_API_KEY": "your-40-character-api-key-here"
       }
     }
     

   • Save the file and restart OpenClaw or reload the session

API Usage

All API requests are made to https://api.nal.usda.gov/fdc/v1 with authentication via the X-Api-Key header.

Rate Limits

• Standard Limit: 1,000 requests per hour per IP address
• DEMO_KEY Limit: 30 requests per hour (not recommended)
• Rate limit headers (X-RateLimit-Limit, X-RateLimit-Remaining) are included in all responses
• Exceeding limits returns HTTP 429 (blocked for 1 hour)

Commands

Search Foods

Search for foods by keyword using /foods/search endpoint.

Usage:

./skills/fdc-api/scripts/fdc_search.sh "search query" [pageSize] [dataType]

Parameters:

• search query (required): Keywords to search for (e.g., "cheddar cheese")
• pageSize (optional): Number of results to return (1-200, default: 10)
• dataType (optional): Filter by data type - "Branded", "Foundation", "Survey (FNDDS)", "SR Legacy"

Example:

./skills/fdc-api/scripts/fdc_search.sh "apple" 5
./skills/fdc-api/scripts/fdc_search.sh "milk" 10 "Foundation"

Response Format: Returns a formatted table with:

• FDC ID (use this to get full details)
• Description
• Data Type
• Brand Owner (if applicable)

Get Food Details

Retrieve detailed nutritional information for a specific food by FDC ID.

Usage:

./skills/fdc-api/scripts/fdc_food.sh <fdcId> [format] [nutrients]

Parameters:

• fdcId (required): The FDC ID of the food (from search results)
• format (optional): "abridged" or "full" (default: "full")
• nutrients (optional): Comma-separated list of up to 25 nutrient numbers to filter (e.g., "203,204,205")

Example:

./skills/fdc-api/scripts/fdc_food.sh 168917
./skills/fdc-api/scripts/fdc_food.sh 168917 full "203,204,205"

Response Format: Returns formatted output with:

• Food description and basic info
• Data type and identifiers
• Nutritional information (formatted as a table)
• Ingredients (for branded foods)
• Serving size information (when available)

Error Handling

Common error codes and their meanings:

• 403 API_KEY_MISSING: No API key provided → Trigger onboarding flow
• 403 API_KEY_INVALID: Invalid API key → Ask user to verify key
• 429 OVER_RATE_LIMIT: Rate limit exceeded → Wait 1 hour before retrying
• 404 NOT_FOUND: Food ID not found → Check FDC ID is correct

Workflow Examples

Example 1: Find nutritional info for a food

1. Search for the food: ./skills/fdc-api/scripts/fdc_search.sh "banana" 5
2. Note the FDC ID from results (e.g., 173944)
3. Get full details: ./skills/fdc-api/scripts/fdc_food.sh 173944

Example 2: Compare multiple foods

1. Search for first food and get details
2. Search for second food and get details
3. Compare nutritional information side-by-side

Nutrient Number Reference

Common nutrient numbers for filtering:

• 203: Protein
• 204: Total lipid (fat)
• 205: Carbohydrate, by difference
• 208: Energy (kcal)
• 269: Sugars, total including NLEA
• 291: Fiber, total dietary
• 301: Calcium
• 303: Iron
• 304: Magnesium
• 305: Phosphorus
• 306: Potassium
• 307: Sodium
• 401: Vitamin C

To filter by specific nutrients, pass them as comma-separated values:

./skills/fdc-api/scripts/fdc_food.sh 168917 full "208,203,204,205"

Notes

• The API returns deeply nested JSON; this skill processes it into readable markdown tables
• For branded foods, brand owner and GTIN/UPC codes are included
• Foundation and SR Legacy foods include NDB numbers
• Survey foods include food codes and portion data