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

Goes well beyond the readOnly/idempotent annotations by explaining failure semantics: transferable can be null when the registry was unreachable, and that null is explicitly not the same as locked. It also clarifies price meaning ('what the transfer would cost if it goes ahead') and the constraint that no auth code belongs here.

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 core action and price scope are front-loaded in the first sentence, and the auth-code warning is placed last as a guardrail. The enumeration of ten reason codes is somewhat verbose given an output schema exists, but each item carries disambiguation value, particularly the note that not_registered means 'register it instead'.

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?

Given a one-parameter batched tool with annotations and an output schema, the description covers everything an agent needs: batch limit, read-only nature, the meaning of the tri-state transferable field, and the pricing semantics. No gaps remain that would cause a misinvocation.

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 single parameter is already documented, but the description adds useful meaning: each element is resolved against its own registry, which implies mixed TLDs are acceptable in one call, and it restates the 5-name ceiling as an operational limit. That is modest added value above the schema.

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 — querying each name's registry for transferability — plus the secondary function of quoting the first-term transfer price in USD. This clearly distinguishes it from sibling tools that deal with availability (check_domain) or TLD policy (get_tld_requirements).

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 concrete usage boundaries: up to 5 names per call, read-only, and an explicit prohibition ('Never send a transfer authorization code here: the transfer itself asks for it') that routes the agent to a different action. It also hints at a follow-up path ('not_registered ... register it instead'). It stops short of naming sibling tools like check_domain for availability-only lookups, so it is clear context without explicit alternatives.

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