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 new behavioral context no structured field carries: a per-call price, the x402 payment rails (Base, Solana, Arc), and the fact that failed calls are not charged. Remaining gaps like result ranking or rate limits are minor.

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?

Three tight sentences: identity and returned fields first, the scope limitation second, and the cost/payment terms last. No sentence repeats the schema or annotations, and nothing is padding.

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?

For a two-parameter read-only search with an output schema and full annotation coverage, the definition supplies everything an agent needs: input intent, what the results contain and omit, and the cost model that affects whether a call is worth making.

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 coverage is 100%, with both query (2-60 chars) and limit (1-10, default 5) fully documented in the schema. The description only restates that the input is a food name; baseline 3 is correct when the schema does the heavy lifting.

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 specific verb+resource ('USDA FoodData Central food search'), enumerates the returned fields (FDC ID, description, data type, brand owner, publication date), and narrows scope with 'for a food name.' It also explicitly excludes a common false expectation ('nutrient values are not returned here'), which is more than any sibling would need to clarify.

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?

The 'Search results only; nutrient values are not returned here' clause tells an agent when this tool stops being useful, and the 'for a food name' phrasing indicates the required input style. It stops short of naming an alternative tool for nutrient lookup, so it is clear context without explicit routing.

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