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

Goes well past the annotations: it discloses that pending/unprobed are never registration claims, that unregistered does not mean purchasable (reserved and premium names answer identically), that only a registrar quote settles price, and that scan_id pagination converges in about three calls. The pricing invariant ('identical for all buyers regardless of budget; budget only changes recommendation and ordering') is exactly the kind of semantic an agent cannot infer from readOnlyHint/openWorldHint. No contradiction with the read-only, non-destructive annotations.

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?

Front-loaded with purpose and classification, then caveats, and every sentence carries operational meaning. It runs long, and the two emphatic sentences about budgets repeat a pricing invariant at a volume disproportionate to this tool's core job, which slightly dilutes focus.

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 return values need not be described, and the remaining gaps are covered: classification meaning, the scan_id continuation loop, purchase-vs-registration caveat, and cost safety. With zero required parameters, the description still makes clear that either query or scan_id drives the call.

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%, so per-parameter semantics are already documented and the baseline is 3. The description earns extra credit by explaining the scan_id lifecycle – that it replaces query/tlds and walks deeper into the same namespace with convergence over roughly three calls – which is behavioral meaning the schema field text does not convey.

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: 'Generates candidate names across a namespace from a concept' and classifies each by registry status. The classification taxonomy (unregistered/registered/pending/unprobed) further sharpens what the tool produces. It does not explicitly name siblings like recommend_name or score_name, so differentiation is inferred from the 'wants options to look at' framing rather than stated.

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?

'For when the user is choosing or inventing a name and wants options to look at' gives a clear use context, and the scan_id guidance ('passing it back walks deeper... converging over about 3 calls') tells the agent how to continue a session. It lacks an explicit exclusion naming the alternative tool (e.g. use recommend_name when a budget-ranked pick is wanted), so the routing is implied rather than spelled out.

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