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

With no annotations, the description carries the full burden and does it well: it discloses price ($0.001 USDC on base via x402), the no-account/no-API-key auth model, the free tier of 500 calls/day, and — importantly — that results come from the provider's own probe record rather than the service's claims. It omits error/not-found behavior and return shape, keeping it short of a 5.

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?

Sentences are short and front-loaded with the core purpose, then pricing, then flow, then value proposition. Price is stated twice ($0.001 up front and again in the payment line) and the staccato fragments are slightly choppy, but almost every sentence earns its place.

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 tool with no annotations and no output schema, the description covers the essentials an agent needs: what is checked, how to pay, cost, free tier, and data provenance. It stops short of describing behavior on an unknown/invalid target or any concurrency/rate limits beyond the free tier.

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 both `target` and `payment` are already documented, including the omit-vs-supply semantics of `payment`. The description repeats the payment flow and price rather than adding new parameter meaning (e.g., what target formats are accepted), so this lands at the baseline 3.

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 states a specific verb+resource (pre-flight check of an endpoint) and enumerates exactly what is answered: liveness, how long known, protocols, price, and whether real money has reached it. This implicitly distinguishes it from single-signal siblings like get_liveness_history or price_check, though it never names 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?

It explains the two-step invocation (call without `payment` to get requirements, call again with `payment` to be served), which is genuine usage guidance. However, it gives no when-to-use/when-not framing relative to the many overlapping siblings (payment_evidence, price_check, get_liveness_history), so the agent must infer routing.

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