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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the safety profile is covered. The description adds genuine behavioral context by disclosing what data is present (NHTSA records for a platform) and, importantly, what is absent (live open/closed status per VIN), preventing a common misuse.

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 tightly written sentences, front-loaded with the core scope and followed by the important caveat and sibling reference. No redundant phrasing or filler.

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 one-parameter read-only lookup with full schema coverage and rich annotations, the description supplies everything needed: scope, returned fields (compensating for the absent output schema), and the key limitation. Nothing an agent needs in order to call it correctly or interpret results 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 description coverage is 100% and the single parameter already says 'Platform id from list_platforms'. The description only reinforces that the scope is one engine platform at a time, adding no new syntax, format, or constraint details beyond the schema.

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 ('NHTSA safety recalls on record for one engine platform') and enumerates the returned fields (campaign number, date, component, model years, summary), so the agent knows exactly what comes back. It also names the sibling get_page and clarifies that this is a subset of the recalls page.

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?

Clearly signals the boundary case: 'Whether a recall is still OPEN on a specific VIN is not known here', which steers the agent away from using this for per-vehicle recall status. It also points to get_page for defect investigations and manufacturer bulletins, though it does not explicitly name lookup_vin as the alternative for VIN-level open recalls.

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