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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds real value beyond that: it discloses what the response includes (owner, expiry) and warns that a negative result does not imply the DNS domain is purchasable — a non-obvious caveat an agent would otherwise miss.

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, front-loaded with the core behavior, followed by one high-value caveat. No filler or redundancy.

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 single-parameter read tool with no output schema, the description sufficiently covers what is returned and what a null result means. The only meaningful gap is sibling disambiguation against resolve_name and reverse_lookup.

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 the schema already enumerates accepted formats (DNS, .cns, .eth) with length bounds, so the baseline of 3 applies. The description adds no format or naming syntax beyond what the schema states.

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 pair: checking whether a name is registered in the Web3 DNS registry, plus what the result includes (owner and expiry). It does not name or distinguish itself from siblings like resolve_name or reverse_lookup, so an agent must infer the boundary.

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 the description ('check whether a name is registered'), but there is no explicit when-to-use versus resolve_name (which presumably maps name to address) or reverse_lookup. The caveat about buying domains is interpretive context rather than routing guidance.

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