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

Beyond the annotations, the description discloses a concrete rate limit (100 cold page reads per owner per UTC day) and failure semantics ('a failed or partial query preserves the last complete observation and its date'), which is exactly the kind of state-safety detail an agent needs. It is also consistent with readOnlyHint=false and idempotentHint=false, since refreshing stored observations is a mutation that can consume quota. It stops short of describing what a successful response contains.

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?

The opening sentence is well front-loaded, but the text repeats itself almost verbatim: 'Does not enable monitoring or make a purchase' is restated as 'This call does not enable a monitor or buy access', and 'Reuses fresh public data' is restated as 'Reuse fresh observations'. Roughly a third of the description is duplicated content that dilutes the load-bearing details.

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?

This is a non-idempotent, open-world, quota-consuming operation with no output schema, so the description carries the burden of explaining results — yet it never says what the refresh returns or how to read the preserved observation. Quota and failure behavior are covered well, but the result contract is left implicit.

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 100% and both parameters (id, guest_token) are documented in the schema itself, including the X-Guest-Token header usage. The description adds nothing about parameter meaning, so the baseline of 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 action (refresh/re-check) and enumerates the resource scope: registration, contacts, TLS, DNS, mail policies, certificate issuance, plus a limited DNS/TLS sample. That is far more informative than the bare title 'Check domain'. It never names a sibling directly, but the explicit 'does not enable monitoring or make a purchase' carves out territory relative to configure_domain_monitor and buy_plan.

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 real usage guidance in 'Reuses fresh public data' / 'Reuse fresh observations', which tells the agent not to call when cached observations are current, plus two exclusions (no monitoring, no purchase). However, no alternative tool is named for the excluded cases, so the agent must infer that configure_domain_monitor or buy_plan are the right routes.

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