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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description does add real value by disclosing the response scope (mileage and tire-pressure logs), which is useful since there is no output schema. It says nothing about 404/error behavior, auth scope, or rate limits.

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?

A single front-loaded sentence states the operation, the input, and the returned data. The trailing 'Shopmonkey: GET /v3/vehicle/:id' is redundant for an agent but cheap and aids API traceability, so it does not meaningfully detract.

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 single-parameter read tool with readOnlyHint set and no output schema, the definition covers purpose, input, and the notable parts of the return payload. The remaining gap — error behavior when the id is unknown — is minor at this complexity level.

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?

Only one parameter, and the schema already documents it at 100% coverage ('The vehicle id.'). The description's 'by id' confirms rather than extends the schema, so baseline 3 is appropriate — there is no format, prefix, or sourcing detail added.

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 (fetch) plus resource (a single vehicle) and the key identifying input (id), and adds what the payload carries (mileage and tire-pressure logs). It implicitly separates itself from list_customer_vehicles by saying 'single', but never names that sibling, so differentiation is inferential rather than explicit.

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?

'by id' implies the usage context: you already have a vehicleId and want the full record. There is no stated when-not, no mention of list_customer_vehicles as the alternative when you lack an id, and no prerequisites or error handling guidance.

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