Evidence (reviews and professional tests)

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower; the description adds genuine behavior beyond them: pagination loop semantics and the important caveat that 'a short page sample does not prove a test does not exist', plus the scope note that a test result applies to its tested size only.

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-loads the purpose, then layers constraints and pagination guidance in short declarative sentences with no filler. The consistent backtick markup is slightly heavy but each sentence earns its place.

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?

With an output schema present, return values need not be re-explained, and the description still covers the non-obvious gaps an agent needs: absent filters, tested-size scoping, and pagination termination. Adequate and then some, though it does not flag the maxItems/page-size bounds.

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%, so the schema already documents page, years, seasons, per_page and automobile_type. The description enumerates returned row fields (slug, title, year, tire_size, etc.), which is output metadata rather than added parameter meaning, so 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?

States a specific verb and resource ('List professional tire tests') and immediately distinguishes itself from the sibling getter by noting it returns the 'slug (the identifier tires_get_test takes)'. An agent can tell list-vs-get apart without opening either schema.

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?

Explains filtering limits ('no upstream list filter by size, brand or publisher') and how to page ('Follow next_page while has_more'). It stops short of naming a preferred alternative such as tires_search for filtered lookups, so usage is clear but not fully routed.

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