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

No annotations are supplied, so the description carries the burden and mostly does: it discloses ordering ('newest activity first'), the identity scope ('the signed-in person'), and the shape of each record (latest scan score, delta vs. prior scan, trend). It omits result-set limits or pagination behavior and any permission caveats, which matters for a list operation with no parameters.

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, both earning their place: the first defines what is returned, the second routes the agent to downstream tools. Front-loaded with the core action rather than burying it.

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 output schema and no annotations, the description must convey return semantics, and it names the three per-site fields plus ordering. It leaves open how many sites are returned and whether the list is truncated, a small but real gap for an unpaginated list 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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly implies no filtering arguments are accepted.

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 verb and resource ('List the sites the signed-in person follows'), scopes it to the caller, and specifies ordering and returned fields. It is clearly distinguishable from siblings like site_history or list_checks, which are per-site or per-check rather than a site inventory.

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?

Explicitly positions the tool as a starting point: 'Use a host from here with site_history, set_pins and the other site tools,' which tells the agent the output feeds other calls. It stops short of an explicit when-not or a named alternative for listing sites, so it falls short of 5.

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