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

Annotations indicate destructiveHint=true and idempotentHint=true. The description adds significant context: it explains that the tool returns unsigned calldata, requires user signing and submission, and that after mining Seaport marks the order invalid. It also details atomic cancellation behavior with alsoCancel. No contradictions with 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?

The description is concise and well-structured, with a clear opening sentence and practical details in subsequent sentences. While it uses multiple paragraphs, it is front-loaded with the core purpose and avoids unnecessary fluff. Could be slightly more terse but remains effective.

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?

Despite lacking an output schema, the description fully explains the return value (unsigned Seaport cancel() transaction calldata) and covers operational context: prerequisites, on-chain behavior, atomic cancellation, and cross-posting considerations. It is complete for a mutation tool with destructive and idempotent hints.

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%, providing a baseline of 3. The description adds meaningful context for parameters: orderHash source ('from get_name_details or the orderbook'), alsoCancel purpose ('sibling order hashes to cancel atomically'), and walletAddress constraint ('must match the original offerer'). This elevates it above the baseline.

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?

The description clearly states it cancels an active ENS name listing via Seaport's cancel() and distinguishes from the sibling tool cancel_offer. It uses specific verbs and resources ('cancel an active ENS name listing', 'submit Seaport's cancel()') and explicitly differentiates from cancel_offer for offers.

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?

The description provides explicit usage guidance: only the original seller can cancel, and for cross-posted listings both order hashes should be passed as alsoCancel. It also directs users to cancel_offer for cancelling offers as a buyer, giving clear when-to-use and when-not-to-use advice.

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