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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so safety is covered. The description adds genuinely useful context beyond that: private options require the account session, public observations are shared by registry domain and HTTPS origin while private settings/history stay with the account, collection gaps and source dates exist, and 'Missing data is not a healthy result.' These disclose data-scoping and freshness behavior the annotations do not.

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 definition is a series of short, front-loaded sentences, but several are cryptic fragments ('Read source dates and collection gaps.', 'Pages share public observations by registry domain and HTTPS origin.') that read as implementation notes rather than agent-facing guidance. Nothing is gratuitously long, but the disjointed flow hurts scanability.

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 readOnly/idempotent annotations present and no output schema, the description carries most of the remaining burden and does so reasonably: it names the observation categories, flags freshness/gaps, separates public-shared from private-account data, and warns that missing data is not a pass. The main omission is any guidance on scope relative to the many sibling domain-checking tools.

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 only 50%: 'id' is documented as an owned tab ID from list_tabs, but 'guest_token' has no schema description. The text partially compensates by implying that private options require the account session (as opposed to a guest token), but it never explains what guest_token grants or how it interacts with the session. Partial compensation justifies the baseline 3.

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 enumerates what is read (registration, contact visibility, TLS, DNS, CAA, mail policies, certificate issuance, limited server comparison), which conveys the general domain-status purpose. However, it never states a crisp verb+resource scope, and nothing distinguishes it from siblings like check_domain, health, audit_url, or lab_result, which also sound like domain/service inspection tools. An agent cannot confidently route between them from this text.

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 when-to-use guidance, no prerequisites, and no mention of alternative tools for narrower checks. Statements like 'A discovered name never starts monitoring automatically' describe behavior rather than selection criteria, so the agent must infer when domain_status is the right call versus check_domain or run_tab.

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