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

Annotations only say read-only and open-world; the description adds material behavior the agent cannot get elsewhere: a hard cap of 10 results per call and a pay-per-call model ($0.002 USDC via x402 on Base, Solana, or Arc) where failed calls are not billed. That pricing detail is critical pre-invocation context. It stops short of describing result ordering or what counts as a 'failed' call.

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?

Single dense paragraph, front-loaded with what the tool returns, then scope, then limits, then pricing — a sensible order with little waste. Slightly compressed but every clause carries information.

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 an output schema present, the description need not explain return shape, and it still names the key fields; pricing and call limits, the two things an agent must know before invoking, are covered. Nothing needed for a correct call is missing.

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%, so both parameters are already documented in the schema. The description only restates the 'product word' matching concept and the 10-result cap, adding minimal meaning beyond the schema's own 'letters and spaces, 2 to 60 characters' and '1 to 10 (default 5)' notes. Baseline 3 applies.

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 and resource ('FDA drug recall enforcement reports matching a product word') and lists the fields returned, so an agent knows exactly what it retrieves. It also scopes the domain with 'Drug recalls only, not food or cosmetics,' which separates it from other FDA dataset siblings, though it doesn't name a sibling tool by name.

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 exclusion clause 'Drug recalls only, not food or cosmetics' tells the agent one clear case where this tool is wrong, which is genuine usage guidance. However, no alternative tool is named for the out-of-scope cases and no prerequisites (e.g. query format expectations) are given beyond the schema.

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