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

With readOnlyHint and openWorldHint already declaring the safety profile, the description adds real context: null semantics ('null when there is none', 'A part of that answer is null where the data is not held'), pagination (pass next_cursor back as cursor), and disclaimers that a description is not a diagnosis and bulletins are model-year, not vehicle-confirmed.

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 resource and coverage scope, then a per-action breakdown. It is dense and long but each clause carries information (examples, null behavior, caveats) with little 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 7-parameter, 3-action tool with no output schema, the description covers every action, example values, null behavior, and result caveats. Only the limit parameter is unexplained, which is a minor gap given the otherwise thorough coverage.

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 only 29%, so the description must compensate, and it largely does: code (example 'P0420'), query (text in code, title or meaning), system (powertrain/body/chassis/network or an area), cursor, id (example vehicle id), and action semantics are all explained. limit is left undocumented in both schema and description.

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?

Names a specific resource (OBD-II trouble codes in Wenmar Open's words), enumerates the scope of coverage (P0, P2, P3400+, B0, C0, U0, U3; manufacturer-specific excluded), and lists the three actions. An agent can tell exactly what this returns and how it differs from bulletin/recall siblings.

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 routes between the three actions with their required inputs (get=code, search=query/system, vehicle=id+code). It does not explicitly say when to prefer this tool over wenmar_bulletins or wenmar_recalls even though it mentions their data, so there is no alternative/exclusion guidance.

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