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

Annotations already establish readOnly, idempotent, openWorld and non-destructive behavior, lowering the disclosure bar. The description adds a genuinely useful behavioral caveat beyond the structured fields: many low-volume vehicles are never tested, which anticipates empty results. It still does not describe rate limits or result formatting, but output schema is absent and the added caveat is meaningful.

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 sentences, front-loaded with the resource and rating dimensions, followed immediately by the usage condition and a caveat. Every clause earns its place with no repetition 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 read-only lookup with full schema coverage and complete annotations, the description adds the remaining needed context: what ratings are returned, when to use it, and the common no-test-data case. Nothing an agent needs to call it correctly 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% and each of the three parameters has a clear description including examples and constraints. The description only restates 'by make, model and model year,' adding no semantic detail beyond what the schema already provides, so baseline 3 is appropriate.

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 (Get) and resource (NHTSA 5-Star Safety Ratings) and enumerates the exact rating categories returned (overall, frontal crash, side crash, rollover, rollover risk). It also scopes the lookup to a tested variant by make, model and model year, which distinguishes it from sibling recall/complaint tools without opening their schemas.

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?

Explicitly says when to use it: 'Use when the user asks how safe a car is or wants to compare crash-test results.' That is clear context, though it does not name alternatives such as check_vehicle_by_vin or state when not to use this tool (e.g. for recalls or complaints).

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