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

Given the readOnlyHint annotation, the description adds substantial behavioral value beyond the annotation: it explains that findings clear statistical floors, that empty results mean nothing looks broken, that error samples are sanitized, and that deployed annotations are attributed as the nearest plausible cause. This gives the agent realistic expectations about sensitivity, privacy, and failure attribution.

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 but front-loaded with the core purpose and maintains focus on what the agent needs: signal types, fields, meaning of empty results, and timing. It is a long single sentence in places, but every clause contributes a distinct useful fact rather than padding.

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 an output schema present, the description does not need to explain full return structure, but it still covers the essential operational context: when to run it, what a null result means, and what categories of findings to expect. The only minor gap is not explicitly routing to a sibling alternative, but the description stands alone well for this diagnostic 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 description coverage is 100%, and the description restates the '7d' default already present in the schema. It does not add significant new meaning for the 'site' parameter, though it does reinforce the default period. 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 identifies a specific diagnostic resource: signs of visitor-facing breakage, including JS errors and behavioral friction like nav_loop and refresh_burst. It clearly distinguishes the tool's purpose from generic query or overview tools by enumerating the concrete signal types, so an agent can understand what this tool uniquely 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 usage instruction: 'Check it after every deploy.' It also clarifies that an empty result is meaningful, which helps an agent interpret output correctly. It does not name alternatives or state when not to use it, but it provides enough context for typical use.

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