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

Annotations mark this as a non-read-only, non-idempotent, non-destructive write, and the description adds substantial behavior beyond that: it returns an unsigned payload that the caller must sign, the exact POST endpoint, the fee mechanism (1% consideration item, seller-paid), and the operator-approval requirement. The one subtlety — the tool itself only constructs a payload rather than mutating state — is still consistent with readOnlyHint=false since a listing is being created. No contradiction.

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 the core action and return type, then layered with fee, scope, prerequisite, and tip sections. Every paragraph carries distinct information, though the multiple trailing notes (fee, NW-native, approval, tips) make it longer than strictly minimal — still, nothing is redundant filler.

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?

No output schema exists, yet the description compensates by describing the return shape (Seaport OrderComponents plus EIP-712 domain/types) and the full signing-and-submission lifecycle. With four parameters at full schema coverage and the mutation path fully spelled out, an agent has everything needed to invoke and complete the flow.

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%, so name, priceEth, walletAddress, and durationSeconds are already fully documented in the schema. The description reinforces ownership ('Must own the name') and fee semantics but adds no syntax, format, or constraint detail beyond what the schema provides. Baseline 3 applies.

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?

Opens with a specific verb + resource + destination: 'List an ENS name for sale on NameWhisper's marketplace via Seaport 1.6.' This clearly distinguishes it from siblings like batch_create_listings, make_offer, and manage_ens_name, which an agent can separate without opening schemas.

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?

Explicitly states prerequisites (approve NameWrapper/BaseRegistrar via approve_operator), recommended pre-steps (get_valuation, get_name_details), the post-signing submission flow, and an exclusion (NW-native only; list on OpenSea separately). Both when-to-use and when-not-to-use are covered with named alternatives.

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