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

With no annotations, the description carries the full burden and discloses real behavioral traits: a hosted payment URL is returned, payment is operator-gated, preparation may be async (retry_after_ms), the request is idempotent by key, and payment buys only this result with no future credit. It omits error/failure behavior, but the async retry and payment semantics are unusually well surfaced.

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 tightly packed sentences with the core action front-loaded ('Prepare one exact task immediately, then return a hosted payment URL') followed by payment, retry, and idempotency constraints. Dense but every sentence carries a distinct, useful fact; no 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?

For a payment/checkout tool with no annotations, no output schema, and 0% schema coverage, the description covers the lifecycle (prepare, retry, pay, no credit) well but leaves the offer selection, terms acceptance, and input payload unexplained. The async retry_after_ms is referenced without any field context, creating a real gap.

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 0% across 5 required parameters, so the description must compensate. It only implies idempotency-key semantics ('never alter its input or key') and says nothing about offer_id, accept_terms, terms_version, or the shape of the nested input object, leaving most parameters undocumented in both places.

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 gives a specific verb+outcome ('Prepare one exact task... then return a hosted payment URL'), which tells an agent this initiates a checkout rather than executing a job. It is distinguishable from run_offer/get_job/list_offers by being a payment/preparation step, though it never names the 'offer' resource the schema centers on.

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?

It gives concrete operational guidance: operator authorization is required to pay, and the same request must be repeated after retry_after_ms while preparation is running, with input/key left unaltered. It stops short of naming when to use this versus run_offer, so there is no explicit alternative routing.

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