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

Annotations already cover safety (readOnlyHint=true, openWorldHint=false), and the description adds genuinely non-obvious behavior: only published parts are returned, unknown fields return the type's field list instead of erroring, and matching semantics differ per value type (case-insensitive substring vs numeric range). It omits ordering and what a result item looks like, but the annotations lower the bar.

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 purpose, then filter semantics, then a single compact example — every sentence carries information. It is dense but readable; the example is justified because the `filters` object is otherwise opaque. Minor cost: the value-type rules and the example overlap slightly.

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?

Covers the nested `filters` object and the fallback behavior well, but with no output schema the description should say what comes back (list of parts with which fields?) and whether `limit` truncates silently. For a search tool with a nested free-form parameter, those omissions matter more than they would elsewhere.

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 schema description coverage at only 25%, the description must carry the load, and it does so for the hardest parameter: `filters` is a free-form object whose number/string/{min,max} semantics are spelled out with a concrete example. `query` is restated (brand+model) and `type` is shown by example, but `limit` (default 20, max 50) is never mentioned.

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 with scope: "Finds published parts of one type by spec." The agent knows exactly what is being searched and that results are limited to one part type. It never names the sibling `part_specs`, so the boundary between searching and inspecting a type's schema is left implicit even though the fallback sentence hints at it.

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 conveyed only through the worked example (type=motor, stator, weight_g max) and the fallback rule for unknown fields. There is no explicit statement of when to call this instead of `part_specs`, nor any note on prerequisites or empty-result behavior. The example makes the intended call shape inferable but not the routing decision.

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