Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the readOnlyHint annotation, the description discloses key behavioral details: values are per 100g with no portion scaling, and failed IDs are returned in a failed[] array rather than aborting the batch. It also strongly recommends the nutrients filter to limit response size. This adds meaningful context beyond annotations and does not contradict them.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is four sentences, each carrying essential information: core purpose, efficiency rationale, unit context, filter recommendation, alternative routing, and failure behavior. No redundancy; front-loaded with the primary action.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The description covers the critical aspects: batch scope, units, failure handling, and recommended filter. An output schema exists (which would explain the success response shape), so its absence here is acceptable. Minor gaps like rate limits or behavior when all IDs fail are not covered, but these are not essential for correct invocation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Both parameters are fully described in the schema (100% coverage), so the baseline is 3. The description reinforces the nutrients recommendation and adds efficiency context, but does not introduce additional format or semantic details for the parameters beyond what the schema already provides.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('Fetch'), resource ('nutrient profiles'), and scope ('2–20 foods in a single API call'). It explicitly distinguishes itself from siblings by noting efficiency over usda_get_food and directing to usda_compare_foods for formatted tables, and references usda_search_foods and usda_list_nutrients for ID discovery.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly tells when to use this tool (batch of multiple FDC IDs, more efficient than repeated calls) and points to an alternative (usda_compare_foods for side-by-side tables). It also reinforces the recommended nutrients filter and warns against large responses. The 2–20 range is stated explicitly, covering the main constraint.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.