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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and openWorldHint, so the safety profile is covered. The description adds genuinely useful context the annotations do not: a cost model with a free daily allowance and $0.003 USDC per call via x402, which affects invocation volume decisions. It stops short of stating the allowance size or auth/payment mechanics.

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 compact sentences with no filler, and the payload description is front-loaded ahead of the pricing note. Nothing is wasted, though the brevity comes at the cost of onboarding detail.

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?

An output schema exists, so return values need not be explained, and annotations carry the safety profile. However, the description omits any guidance on the required search expression format and on how this endpoint differs from the other openFDA drug tools, leaving meaningful gaps for a query-driven API.

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 100% with only two parameters, so the schema already documents limit and search. The description adds no syntax or format detail for the non-trivial openFDA search expression, so 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?

The description names a specific resource (structured prescribing information) and enumerates its content areas (indications, dosage, warnings, interactions), which is enough for an agent to understand what is returned. It lacks an explicit verb and does not distinguish itself from nearby siblings like openfda__drug-adverse-events, openfda__drug-recalls, or openfda__drugs-fda.

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 guidance on when to use this tool versus the many other openFDA drug endpoints or RxNorm alternatives. The only usage-adjacent information is billing (free within daily allowance, then per-call pricing), which says nothing about selection criteria.

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