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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld). The description adds cost/rate-limit context, which is genuinely useful since it is not in the annotations. However, it says nothing about what the search returns, pagination, or what happens when the allowance is exhausted.

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 short sentences with no waste and the pricing constraint front-loaded. Slightly under-specified rather than verbose, but structurally efficient.

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 annotations carrying the safety profile and an output schema present, return format need not be described. But for an openFDA search tool sharing a namespace with many near-siblings, the description lacks scope/disambiguation and any hint of expected usage, leaving a notable gap.

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% – both limit and search are documented in the schema, including the default and max for limit. The description adds no parameter-level detail, 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?

States the resource 'National Drug Code directory entries' and implies lookup, but the sentence is a noun phrase without a verb. Siblings like openfda__drugs-fda, openfda__drug-labels and rxnorm__ndc make it hard to tell what distinguishes this NDC directory from the other NDC/drug tools.

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 only guidance is pricing ('free within the daily allowance, then $0.003 USDC per call'). There is no statement of when to use this tool versus openfda__drugs-fda or rxnorm__ndc/ndcs, and no exclusion criteria.

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