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

Annotations only declare readOnly/openWorld/non-idempotent; the description adds substantial behavioral context beyond them. It discloses the exact cost and payment rails (0.01 RLUSD on XRPL, 0.01 USDC on Base), that an unpaid call returns isError carrying a fresh PaymentRequired invoiceId, the retry path via _meta["x402/payment"] or the signature argument, and that unsuccessful unpaid calls cost nothing.

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?

Three sentences, all load-bearing: pricing/rails, what the report contains, and the unpaid/retry behavior. Information is reasonably front-loaded. It is dense but not padded, and nothing is repeated from the schema.

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 no output schema, the description carries the return-value burden and does describe it at a high level (reachability, valid 402 response, timestamps). It also fully covers the payment/error flow. The only thin spot is the exact shape of a successful report, which stays abstract.

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% and the single parameter is optional, so the baseline is 3. The description earns above baseline by explaining the intended usage pattern for payment_signature (for hosts that cannot set _meta) and by clarifying that omitting it on the first call is the expected way to obtain payment requirements.

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 and resource: a health report covering reachability and valid-402 status for known x402 endpoints and the t54 facilitator, with timestamps. That is enough for an agent to know what it returns. It does not, however, distinguish itself from similarly named siblings such as get_pulse_facilitator, get_service_status, or get_x402_activity.

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?

Usage is implied through the payment workflow: call it, and if unpaid you get a PaymentRequired object to retry with. There is no explicit statement of when to choose this over the many sibling health/status tools, nor any exclusion criteria, so the agent must infer the right context from the name alone.

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