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

With no annotations present, the description bears full burden and delivers richly: it discloses the custody model ('The agent's own wallet signs and submits — this never signs or holds keys'), Dutch-auction interpolation with asOf timing, the approval grant logic (approveBaseUnits slightly above quote, never above maxTotalBaseUnits), and the optional auction cleanup transaction that zeroes residual allowance.

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?

Four dense sentences, each carrying distinct information: purpose and output composition, pricing/approval behavior, auction cleanup, and custody safety. Purpose is front-loaded in sentence one, with no filler and no restating of schema facts.

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 the tool's complexity — no annotations, no output schema, one undocumented parameter — the description covers the return package (summary with asOf quote, approvals, calldata, snapshot, optional cleanup) and key edge-case behavior. Remaining gaps are minor: orderHash provenance/validation and error conditions, plus reliance on Seaport domain jargon.

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?

The single required parameter (orderHash) has 0% schema coverage, and the description never explicitly defines it or states where to obtain it (e.g., from get_listings or get_listing_details). It compensates only implicitly by repeatedly referring to 'the order' (decaying order, maxTotalBaseUnits), so an agent must infer that orderHash identifies the listing/offer being purchased.

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 — 'Prepare the non-custodial transaction package to BUY a listing (or accept an offer)' — and enumerates the package's components: ordered approvals, Seaport fulfillOrder calldata, and a fresh contents snapshot. The buy/fill semantics ('fulfillOrder calldata') distinguish it from sibling prepare_offer, which creates offers rather than filling them.

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?

Provides clear usage context: use when buying a listing or accepting an offer, which contrasts with the get_*/list_* read siblings and the other prepare_* write tools. However, it never explicitly names an alternative or states when-not-to-use, leaving exclusive routing to inference.

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