preflight_check

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

With no annotations present, the description carries the full disclosure burden and does well: it discloses that each check has a short timeout, that check 2 deliberately triggers a 402 without payment, that no USDC is ever spent, and that the result includes an overall ok flag plus per-check status. It stops short of describing failure modes, latency expectations, or whether checks run sequentially or in parallel.

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 header sentence, a scannable numbered list of the five checks, then a return-shape sentence. Slight redundancy between the '[FREE]' tag, 'WITHOUT spending any USDC', and the closing 'No payment required, ever', but the list format makes the length feel earned rather than padded.

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 zero-parameter, annotation-free tool with no output schema, the description supplies everything an agent needs: what is checked, that it is costless, the timeout caveat, and the shape of the response (ok flag + per-check status). There is no material gap left for the agent to guess at before calling it.

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?

The tool takes zero parameters, so there is nothing to disambiguate and the schema (additionalProperties: false, empty properties) already says everything. Baseline 4 applies; the description adds no parameter-level detail because none is needed.

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: verify reachability/health of the AgentWorld MCP and x402 payment rail, and enumerates exactly the five checks performed. The purpose is unambiguous, but it never distinguishes itself from close siblings such as safe_preflight_check, check_payment_readiness, or check_facilitator_liveness, which overlap directly with checks 2 and 3.

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?

The '[FREE]' tag and 'WITHOUT spending any USDC' phrasing imply this should be the first call before any paid flow, which is useful context. However, there is no explicit when-to-use / when-not-to-use statement and no routing to safe_preflight_check or check_facilitator_liveness when only a partial check is needed, so the agent must infer the choice.

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