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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint: false, lowering the transparency burden. The description adds behavioral context by explaining that it 'probes each entity ... with ai_visibility_check, ranks by score, surfaces which is most/least recognized' and returns specific metrics. This goes beyond the annotations without contradicting them, though it does not detail rate limits or error handling.

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 three sentences, front-loaded with the core purpose, then details the mechanism, use case, and output. Every sentence adds value, and there is no redundancy or fluff. It is concise while covering all key aspects.

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?

Despite having no output schema, the description supplies a clear summary of the return value ('ranked list with score, confidence, signal density per entity'). The input schema fully documents parameters, annotations cover safety, and the description explains behavior and use case. This is complete for a read-only comparison tool.

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 baseline is 3. The description adds minimal parameter meaning beyond the schema—it mentions 'your brand + N competitors' but the schema already states that the first entity is the subject. It does not clarify any additional parameter behavior beyond what is already in the input schema, so no higher score is warranted.

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 clearly states the tool's purpose: 'Compare AI visibility across multiple entities side-by-side.' It uses specific verbs and resources, and distinguishes itself from the sibling tool ai_visibility_check by emphasizing multi-entity comparison and ranking. The output is also specified ('ragged list with score, confidence, signal density'), making the purpose unmistakable.

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 provides a clear usage context: 'Useful for competitive AI-marketing audits' with a concrete example ('does Claude know about us as well as our competitors?'). It implies that this tool is for comparing entities, whereas ai_visibility_check is likely for single-entity checks. However, it does not explicitly state when NOT to use it or name alternatives, so it falls 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.