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

Annotations already declare readOnlyHint and idempotentHint. The description adds valuable behavioral details: unresolved profiles return in a notFound list instead of failing, the call costs 2 credits, and it is 'Pure lookup, fast.' This goes beyond what annotations provide, earning a 4.

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 main action and scope. It includes only useful details: output stats, error behavior, and cost. No fluff or 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?

For a read-only tool with no output schema, the description covers inputs (profile id or platform+handle), outputs (stats fields and ranking), error handling (notFound), and cost. It does not clarify whether both handles and profileIds can be mixed, but overall it is complete enough for an agent to invoke correctly.

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?

The schema descriptions already cover both parameters 100% ('Handle pairs to resolve; 2–5 profiles total across both fields' and 'Profile ids to compare'). The description repeats the identifier types and the 2–5 limit but does not add new parameter semantics, 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 clearly states the tool 'Compares 2–5 tracked profiles' and specifies the outputs: stats (follower count, average views/likes, engagement rate) and a computed ranking. This specific verb+resource distinguishes it from siblings like get_profile or search_profiles.

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 clearly implies the use case: comparing multiple (2–5) tracked profiles. It notes 'Pure lookup, fast' and error handling for unresolved profiles, but does not explicitly name alternatives or say when not to use it. Clear context without exclusions warrants a 4.

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