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

Goes well beyond the annotations: it says the call is free, creates no invoice, consumes a per-caller-limited nameserver offer, and therefore explicitly is not read-only — which resolves the apparent paradox of a 'check' tool carrying readOnlyHint=false. The ns_ticket round-trip and its timing dependency (wait for registry publication) are behaviors that exist nowhere in the structured fields.

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?

Three sentences, front-loaded with the free/preflight nature, then the workflow, then the side-effect caveat — nothing is wasted. The middle sentence is long and packs an entire multi-step procedure into one clause chain, which slightly hurts scannability.

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 no output schema, the description carries the return burden and does state it returns the price plus the delegation_missing / expected_ns / ns_ticket payload. It does not say what a successful non-error response looks like beyond the price (e.g. whether individual check results are reported), and other possible error codes are unnamed.

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 the two parameters are already documented. The description still adds real meaning by clarifying that payment arguments inside `arguments` are ignored and by spelling out the extra `ns_ticket` argument that must be added on a retry after delegation_missing — semantics the schema does not surface.

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 — runs the same pre-payment checks a paid call runs, without creating an invoice, and returns the price. It also implicitly distinguishes itself from the paid siblings (zone_create, secondary_create, renew, etc.) by framing itself as their free dry run, so an agent can tell what it does and what it is not.

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?

Gives a clear situation for use (before payment, to learn the price) and a concrete procedure for the delegation_missing case: set the expected_ns records at the registrar, wait for publication, then call again with ns_ticket. It never states the negative case explicitly (if you want the resource actually created, call the paid tool directly), so the exclusion is only implied by 'without creating an invoice'.

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