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

Annotations already declare read-only, idempotent, non-destructive and closed-world behavior, so the bar is lower. The description adds real value beyond them by naming the verified_fit result field and warning that compatibility must never be claimed when it is false — a meaningful interpretive constraint.

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 sentences, front-loaded with the core action and followed by the critical output caveat. Every clause earns its place with no 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?

There is no output schema and no annotations gap in safety, and the description supplies the key return semantics (verified_fit) plus the interpretation rule. The remaining gap is the two brand parameters, which are left unexplained.

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?

With 0% schema description coverage, the description must carry the burden for four parameters. It conveys exact-match semantics for 'part' and 'model' but says nothing about part_brand or model_brand, leaving half the inputs undocumented in both structured and prose form.

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 (verify) and a precise resource/relationship (fitment between an exact part number and an exact appliance model), which is clearly distinct from lookup-oriented siblings. It does not explicitly name which sibling to prefer, so it stops short of a 5.

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?

The use case is implied by 'verify whether ... has a recorded fitment relationship' and the emphasis on 'exact' suggests it is not for fuzzy or substitution lookups, but no explicit when-to-use/when-not or routing to lookup_substitution / lookup_model_parts is given. Usage must be inferred.

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