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

Annotations already state readOnly, idempotent, non-destructive, so the safety profile is free. The description adds real value on top: the underlying data sources (live DVLA MOT and tax), the fact that a pass/fail decision is returned along with 'what to do next', and that the insurance element is a declared answer rather than an API hit. One tension worth noting: 'live MOT and tax from DVLA' implies external interaction while openWorldHint is set false, which could mislead an agent about data freshness/source.

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 what is checked and what comes back before the optional-parameter note. No filler, no repetition of the title, and the 'what to do next' framing earns its place by telling the agent the response is actionable.

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?

There is no output schema, so the description correctly spends words on the return content (pass/fail plus remediation guidance), and with a single nested body parameter the input surface is simple. It stops short of covering failure modes such as no DVLA record, invalid VRM, or rate limits, which matters for a live-data check.

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%, including a detailed explanation of insurance_declared (askMID is a manual, self-declared check) and a VRM example. The description only restates that insurance_declared is optional and takes yes/no, adding no format, constraint, or fallback detail beyond the schema, so the 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?

The description names a specific verb and resource: run a Road Legal Pass over a UK registration, combining DVLA MOT/tax data with a declared-insurance check and a pass/fail verdict. That is far more specific than the tool title alone. It does not, however, distinguish this tool from the near-identical sibling 'vehicle_check_road_legal' (nor from 'road_legal_catalogue'), which is the main clarity gap.

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?

Usage is implied by the opening 'Run the Road Legal Pass over a UK registration' and by the note that insurance_declared can optionally be supplied, which gives some call-time guidance. There is no explicit when-to-use vs. when-not, and no routing to the obvious alternatives like vehicle_check_road_legal or road_legal_catalogue, so an agent still has to guess which sibling to pick.

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