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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuine context beyond that: results are bucketed daily, done moves are marked on the timeline, and each carries a 'what changed since' delta. Pagination and volume limits are unmentioned, but the output schema presumably covers the response shape.

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, no filler, with the data shape stated before the usage examples. The phrasing is dense with domain jargon ('named and linked counts'), which costs a little immediate clarity but not 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?

With an output schema, full parameter documentation and rich annotations, the description only needs to establish what the report contains and when to reach for it, and it does both. The jargon around 'moves' and 'named and linked counts' is the main residual ambiguity.

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 coverage is 100%, with both parameters fully described including the 7/30/90 enum and the 'leave it out for all sites' default. The description's mention of the three windows and per-site breakdown echoes rather than extends the schema, so the baseline 3 applies.

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 names a specific resource and scope: daily named and linked counts per site and per AI over a fixed set of windows, plus completed moves shown on the timeline. That is far more specific than a restatement of the name 'trend'. It does not, however, distinguish itself from siblings like briefing or rival_detail, so an agent must infer the boundary.

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?

Two concrete example questions ('how have I moved this month?', 'did the comparison page work?') give the agent a clear trigger condition for selecting this tool. There are no explicit exclusions or named alternatives, so it stops short of a 5.

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