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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the agent knows it's a safe, non-mutating operation. The description adds behavioral context beyond annotations: it states the tool "Probes each entity ... with ai_visibility_check, ranks by score" and "Returns ranked list with score, confidence, signal density per entity," disclosing internal delegation and output structure. This enriches the annotation-only picture.

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?

The description is four concise sentences, each carrying distinct information: purpose, mechanism, use case, and return value. It's front-loaded with the main action and avoids fluff. No redundancy.

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?

The tool has 4 parameters, full schema coverage, annotations, but no output schema. The description covers what it does, how it does it (probes and ranks), and what it returns (ranked list with score/confidence/signal density). It doesn't mention error handling or edge cases, but for a non-mutating read tool with strong annotations, this is adequate.

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%, and the schema already explains each parameter, including that the first entity is the subject. The description's mention of "your brand + N competitors" reinforces but doesn't add new parameter-level detail beyond the schema. Thus baseline 3.

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 opens with "Compare AI visibility across multiple entities side-by-side," a specific verb+resource that distinguishes it from sibling tools like ai_visibility_check (single entity) and compare_entities. It further details that it probes each entity, ranks by score, and identifies most/least recognized, making the purpose unambiguous.

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 description includes a concrete use case: "Useful for competitive AI-marketing audits: 'does Claude know about us as well as our competitors?'" This tells the agent when to employ it. It mentions it probes with ai_visibility_check, implying that tool is for single-entity checks, though it doesn't explicitly say "use this instead of..." so it's clear but not exhaustive.

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