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

Goes well beyond the annotations: no charge, no reservation, the work can still sell to another buyer, the link works once and lapses at expires_at, and the buyer needs no account. These details reconcile cleanly with readOnlyHint=false (a link is created) and idempotentHint=false (single-use, expiring link). The out_of_stock refusal shape is disclosed, which annotations could never convey.

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 trigger and the returned artifact, then layers constraints and the failure branch in a sensible order. It is dense rather than padded, though the buyer-page narrative (name, e-mail, US delivery address) is slightly more than an agent needs to invoke the tool.

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, so the description carries the full burden — and it names checkout_url, expires_at, and the out_of_stock refusal contents. For a single-parameter tool with clear annotations, nothing an agent needs to call or interpret the result is missing.

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 baseline is 3; the description still adds real meaning by specifying where listing_id comes from (search offer.listing_id, get_artwork listings) and that exactly one is accepted per call. It adds the cardinality constraint the schema cannot express (maxLength aside).

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+resource ('Get a checkout link' for one chosen work) and immediately names the return value (checkout_url) and what it is (a page on Fold's own site for that one work). It also distinguishes itself from adjacent steps by saying it checks availability itself, so no prior call is needed — an agent can place it precisely in the buy flow.

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?

Explicit trigger ('when the buyer has chosen one work and wants to buy it'), explicit no-prerequisite guidance ('call it straight from a search's offer.listing_id or get_artwork's listings, with no other call first'), and an explicit cardinality rule ('one listing_id per call, since each work is its own purchase'). It even covers the failure branch, telling the agent to offer up to three similar works from the out_of_stock refusal.

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