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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context: pages are ordered by sessions and include friction metrics such as average scroll, active time per session, and several click/scroll/script error rates. It does not mention pagination or result limits, but the output schema covers return structure.

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?

Front-loads the core purpose and metric list, then gives usage examples and the device filter. It is appropriately sized, though the long first sentence packs many details together.

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 annotations cover safety, the schema fully documents both optional parameters, and an output schema exists, the description provides enough context to select and call the tool. Minor missing details like ordering behavior beyond 'by sessions' or limits are not essential here.

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 parameters are already documented there, including device values and date_range examples. The description mentions device filtering to separate mobile from desktop, but adds no syntax or semantics beyond the schema; 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?

States a specific resource and operation: site pages ordered by sessions with Clarity friction metrics, including the exact metrics returned. It is not explicitly contrasted with sibling tools like list_clarity_sources or get_clarity_summary, so it falls just short of a 5.

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?

Provides clear usage context with example questions it answers (which page to fix first, where users get frustrated, landing-page UX issues, per-page CRO). It also mentions device filtering to separate mobile from desktop, but does not state when not to use it or name an alternative tool.

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