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

With no annotations, the description carries the full behavioral burden. It does useful work by disclosing the return payload — per-suffix rules, price tiers, DNSSEC, plus meta (registration enabled flag, per-transaction year limit, grace period days, unitName/unit) — which tells the agent what state it can read. It says nothing about auth requirements, rate limits, or whether the catalog is cached/static.

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?

One dense sentence that front-loads the action and resource, then the payload contents. The parenthetical enumerations are long but every item is substantive rather than filler, so nothing reads as 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?

For a no-parameter read tool with no annotations and no output schema, the description is the sole carrier of return-shape information and it does describe the catalog fields and registration meta. It is nearly complete; only the sibling-overlap and auth story are unaddressed.

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 focuses on output content instead of inventing parameter semantics.

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 ('List') and resource ('public suffix catalog open for registration'), then enumerates the returned attributes (label length rules, price tiers in points, DNSSEC availability, registration meta). This is clearly distinguishable from domains_get/domains_check, though it never acknowledges the near-identical sibling admin_list_domain_suffixes, so the agent must guess which surface to use.

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 only implied by 'open for registration' — an agent can infer this is the discovery call before domain_register, but there is no explicit when-to-use, no prerequisites, and no mention of the admin_list_domain_suffixes alternative. Adequate but with a clear gap.

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