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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the list of returned metrics and the kind of question it answers, but does not disclose additional behavioral details such as response shape, date handling, or limitations.

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 short sentences with no filler. The first sentence states exactly what is returned and for what scope; the second explains the analytic use case. Every word earns its place.

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?

For a read-only summary tool, the description lists the key metrics and the question it answers, while the schema covers parameter details. There is no output schema, but the description gives a sufficient mental model of what the tool returns. It could be slightly more explicit about how 'changed' is represented, but overall it is adequate.

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 83%, so the schema already documents most parameters. The description only loosely maps to 'site and period' via site_id and period/date, adding little semantic meaning beyond what the input schema provides.

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 uses a specific verb ('Return') and a clear resource: Matomo visits, unique visitors, actions, bounce rate, visit duration, and conversions. It also states the analytic purpose ('Answers how traffic volume and engagement changed'), which distinguishes it from sibling tools focused on goals, pages, or referrers.

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 conveys a clear context for use: answering questions about traffic volume and engagement for a site and period. It does not explicitly name alternatives or exclusion criteria, but the use case is evident enough for an agent to choose this over the more specialized Matomo sibling tools.

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