Compare car specs

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

Annotations already declare readOnly, idempotent, non-destructive and open-world, so the safety profile needs no restating. The description adds one genuinely useful behavioral fact — result values follow the `cars`/input order — but says nothing about cost, response size for four-variant comparisons, or how missing variants are handled. Credit for the ordering note, but it is thin beyond annotations.

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 short paragraphs, front-loaded with what the tool returns, followed by workflow and sibling routing. No filler sentences and no repetition of schema content.

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 no output schema, the description correctly shoulders the burden of describing the return shape (score, pros, cons, spec rows) and the input source. The one loose end is the ambiguous reference to `cars` when the parameter is `slugs`, which could briefly puzzle an agent mapping order semantics.

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 both parameters are already documented in the schema (including the slug pattern and only_differences default). The only added meaning is the output-ordering guarantee tied to input order, which is modest. Baseline 3 is appropriate.

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?

"Compare two to four car variants side by side" gives a specific verb (compare), resource (car variants) and explicit arity bound, then enumerates what comes back (review score, pros, cons, spec rows). That cleanly separates it from kn_specs_search (slug lookup) and kn_specs (single-variant detail) without opening a 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?

It names the triggering question shape ("A or B?") and the required precondition (slugs found via kn_specs_search), then routes adjacent needs to siblings: kn_price_list for new prices and kn_cars for used-market asking prices. When-to-use, prerequisite and alternatives are all present.

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