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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real behavioral detail beyond that: the exact status vocabulary, that open changes include before/after diffs, and that recency is expressed both as last checks and as days without a break — enough to predict what comes back and whether it answers a 'what changed' question.

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?

A single compact sentence with the resource front-loaded and the returned facets listed after. Every clause carries information; only minor cost is the slightly telegraphic 'ok, changed, break' phrasing.

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 no parameters, no nested objects, and no output schema, the description's only remaining job is to convey return shape and it does so concretely (status states, before/after diffs, last checks, days without break). Nothing an agent needs in order to decide to call it is missing.

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 tool takes zero parameters, so the baseline is 4. The description correctly implies no filtering or scoping inputs are needed — it returns the full watched-sites set — and does not mislead about any options.

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 the resource (watched sites) and enumerates the specific contents: status values with fixed vocabulary (ok, changed, break), open changes with before/after, last checks, and days without a break. It implicitly separates this from get_sites (all sites) and list_scans, though it never explicitly contrasts with them.

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?

There is no explicit when-to-use statement, no prerequisites, and no named alternative. An agent must infer that this is the read path complementing watch_site and recheck_page purely from the wording 'Your watched sites'.

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