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

Beyond the readOnlyHint annotation, the description discloses important behavioral details: findings clear statistical floors, so an empty result is meaningful; samples are sanitized; each error is tied to the nearest deploy annotation. This tells the agent how to interpret empty versus non-empty results, which is critical for correct use.

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 dense and packed with useful detail, without filler. It is a single long sentence, but every clause adds relevant information about signal types or interpretation. It is not maximally concise due to the parenthetical-heavy structure, but it earns its length.

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?

Given that an output schema exists and the annotations cover the read-only safety profile, the description provides sufficient context: signal categories, their fields, statistical floors, empty-result meaning, and a clear call to action. An agent can correctly decide when and how to use this 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?

The input schema already documents both parameters with 100% coverage, including the period default. The description repeats the '7d' default but adds no new parameter-level meaning beyond what the schema provides. Baseline 3 is appropriate since the schema carries the parameter documentation burden.

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 identifies the tool's purpose: surfacing signs of visitors hitting problems (JS errors and behavioral friction) in a period. It names specific signal types (new_error, error_spike, nav_loop, refresh_burst) and what each contains, making it distinguishably about breakage detection rather than generic analytics. The title and description together leave no doubt about what the tool reports.

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 gives an explicit, actionable usage instruction: 'Check it after every deploy.' This tells the agent exactly when to invoke the tool. It does not explicitly list alternatives or when-not-to-use scenarios, but the deploy-triggered guidance is strong and contextually sufficient.

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