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

Annotations already declare readOnly, idempotent, and non-destructive, so the safety profile is covered. The description adds valuable behavioral detail: it internally calls ai_visibility_check per entity, ranks by score, and returns score/confidence/signal density. This goes beyond the annotations without contradicting them.

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?

Three sentences, front-loaded with the main action, followed by an illustrative example and a concise list of return fields. Every sentence earns its place with no filler or repetition.

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 compensates by specifying the return format (ranked list with score, confidence, signal density) and the use case. It also mentions the internal probe mechanism. Given the tool's orchestrated multi-entity nature, this is quite complete, though it could optionally mention model-dependent behavior (already in schema).

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 100%, so the schema already documents all four parameters clearly. The description reinforces that the first entity is the subject and the rest are competitors, but that detail is already in the schema. No additional parameter-specific meaning is provided, so 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?

The description uses a specific verb ('Compare') and resource ('AI visibility across multiple entities side-by-side'), clearly distinguishing it from the single-entity sibling tool ai_visibility_check. It explicitly states it probes, ranks, and surfaces most/least recognized, leaving no ambiguity about its function.

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 provides a clear use case ('competitive AI-marketing audits') with an example question, implying this tool is for multi-entity comparisons rather than a single check. However, it does not explicitly name alternatives or state when not to use it, so it falls just short of a 5.

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