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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds the side-by-side comparison framing but says nothing about output shape, limits, or how missing/private accounts are handled, so it clears only the lower annotated 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?

Two sentences, zero filler, with the action and scope front-loaded before the usage triggers. Every clause adds information.

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 three fully documented params, annotations covering the safety profile, and no output schema to explain, the description covers what an agent needs to select and invoke it. A brief note on result shape or handling of fewer than 2 usernames would close the remaining gap.

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 both enums are fully documented in the schema, so parameter meaning is already carried by structured data. The description names the same metrics as the enum, adding no format, default, or interaction guidance (e.g., how 'metric' affects the output), which lands at the 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 states a specific verb and resource ('Compare 2-5 TikTok accounts side by side') and enumerates the metrics compared (engagement rate, follower growth, total plays, posting frequency), so the agent knows exactly what the tool returns. It does not, however, distinguish itself from the sibling 'compare_accounts', leaving ambiguity about which comparison tool to pick.

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 gives clear positive triggers: benchmarking accounts against each other, comparing TikTok competitors, or identifying the best-performing account. There are no exclusions or named alternatives, so the agent must infer when to prefer the generic 'compare_accounts' sibling.

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