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

Adds substantial context beyond the annotations: payment is over x402, Paylyte does not spend a wallet, a missing payment yields a 402 challenge containing priceUsd and maxAmountRequired, unknown paths are refused, and the tool does not write or edit Core. These are exactly the behavioral traits (cost, failure mode, retry policy, side-effect boundary) an agent needs before invoking a paid endpoint.

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-loads the core instruction and the priceUsd prerequisite. It is a touch repetitive ('Read priceUsd first' vs 'Do not retry payment until you have read priceUsd', the latter duplicating the schema), but every sentence still carries actionable content.

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?

With annotations covering the safety profile, the description covers the purchase flow, the 402 failure path, and refusal conditions, so an agent can call it correctly. It stops short of describing the successful paid response, which is the one remaining gap for a purchase tool with no output schema.

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 the schema already documents every parameter, including the meaning of payment, path, and the per-path-only params. The description mostly restates the priceUsd/402 guidance already present in the schema, adding little parameter meaning of its own; baseline 3 is appropriate.

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 ('buy one live paid offering from the catalogue') plus the payment mechanism (x402). It is plainly distinguishable from discover_live_offerings, which only lists offerings, and it names scope constraints (no writes to Core).

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?

Gives clear preconditions: read priceUsd first, do not retry payment until priceUsd is read, and only paths from the catalogue are accepted. The discovery step (discover_live_offerings) is implied via 'the catalogue you already see' but never explicitly named in the description as the routing alternative.

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