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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered; the description adds genuinely useful behavior beyond that, namely the per-call cost ($0.003 USDC via x402) and the paid-call model. It stops short of describing result limits, pagination, or failure modes.

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?

Two dense sentences: the first front-loads what data is returned and from where, the second carries the cost constraint. Nothing is padding and the most decision-relevant facts lead.

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?

With no output schema, the description usefully enumerates the returned nutrient fields and discloses the cost, which is enough for an agent to decide whether to call it. The main gap is the undocumented 'limit' parameter and query-input expectations.

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?

Schema description coverage is only 50%: 'q' is described merely as 'Food' and 'limit' is undocumented. The description does not compensate, adding no query syntax, format, or limit behavior, so an agent cannot infer how to form a good query or cap results.

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?

States a concrete resource (nutrition facts for foods and branded products) and names the upstream source (USDA FoodData Central) plus the specific nutrients returned. It is clearly a food-nutrition lookup rather than a recipe or generic search tool, though it does not explicitly differentiate itself from the sibling nutrition_recipe.

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?

There is no when-to-use or when-not-to-use guidance and no mention of alternatives, despite a closely related sibling (nutrition_recipe) that an agent must choose between. Usage is only implied by the phrase 'for foods and branded products'.

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