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

Annotations already establish readOnly, idempotent, non-destructive and open-world semantics, so the safety profile is covered. The description still adds real context beyond that: mpge for EVs, electric range, tailpipe CO2, estimated annual fuel cost, that unshown configurations are listed, and the caveat that these are EPA estimates rather than real-world mileage.

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?

Front-loaded with the usage trigger, then the call pattern, then the return payload, so an agent gets the decision-relevant information first. The return-value inventory is somewhat long and partially redundant with the output schema, but no sentence is wasted.

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?

Rich annotations and an output schema mean the description need not spell out safety or return structure, and it covers purpose, trigger, inputs and a caveat about data provenance. The only gap is routing relative to sibling tools such as get_vehicle_report, which is not addressed.

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 schema already defines make, model, year and option with examples, so the baseline is 3. The description restates the call pattern ('Pass the year, make and model, and optionally words such as AWD or hybrid') but adds no syntax or format detail the schema does not already carry.

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 states a specific verb and resource ('Returns the EPA's city, highway and combined mpg ... for each configuration') and scopes itself to fuel-economy data, which clearly separates it from siblings like decode_vin, get_vehicle_report and list_recalls. An agent can identify the tool from the description alone.

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?

It gives an explicit trigger ('Use this when the user asks about mpg, electric range or fuel cost for a car') plus a concrete example query, which is stronger than implied usage. It does not, however, name a when-not condition or point at any sibling alternative for vehicle data, so it falls short of the top mark.

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