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

Annotations already declare readOnly/idempotent/non-destructive, so "Read-only: it changes nothing" is largely redundant, but "uses no credits" is new and actionable. The stale-check caveat ("an earlier check, not one made now") is genuinely valuable behavioral context that prevents misreading the result as a live probe.

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?

Three front-loaded sentences with the purpose first and the return-shape summary second; nothing is filler. The read-only clause slightly repeats the annotations, which is the only waste.

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?

An output schema exists, so the return contract is optional, yet the description still adds the crucial caveat that the confirmed timestamp reflects a past check rather than a fresh one. The remaining gap is disambiguation from the similarly named status-checking siblings.

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 a single documented designId parameter, so the schema carries the semantics. The description adds no format or sourcing detail beyond what the schema already says, making baseline 3 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 verb and resource ("Checks whether a saved site is live") and the title reinforces it. However, the sibling list contains iter0_check_site and iter0_get_site_status, which sound nearly identical, and the description never says how this differs from 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?

Usage is implied by "saved site" and the freshness caveat signals when the answer may be stale, but there is no explicit when-to-use/when-not or pointer to the near-duplicate siblings (iter0_check_site, iter0_get_site_status) an agent must choose between.

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