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

Goes well beyond the annotations: it discloses that no payment or signature ever occurs, that the target server sees a live HTTP probe, the exact billing boundary, the price and payment rail (USDC on Base, Base-only for MCP), and links the buyer terms. The non-idempotent/hit-or-miss billing behavior is exactly the kind of context annotations alone cannot convey.

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 with the core verb and the safety guarantee, then the added checks, then billing. It is dense and the payTo parenthetical runs long, but nearly every clause carries decision-relevant information (cost, billing edge cases, payment rail).

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 must convey what comes back, and it does by naming the source report and the categories of live findings. Combined with explicit billing and payment constraints for an open-world, paid tool, an agent has enough to call it correctly; only the response shape of the added checks remains vague.

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 url, method and body in comparable detail. The description's 'GET url (optional method, body)' confirms behavior but adds no new semantics such as constraints on url or how body interacts with method beyond what the schema states. Baseline 3 applies.

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+resource (deep check of an x402 endpoint) and immediately scopes it: never pays or signs, returns the full /api/x402-check report plus live checks. The enumeration of what the deep layer adds (TLS, security headers, CORS, payTo verification, lookalike detection, drift across well-known/openapi/CDP Bazaar) makes it clearly distinguishable from the sibling x402_check and bazaar_check.

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 context is implied rather than stated: the 'deep' framing and the cost ($0.03/call) tell an agent this is the heavier, paid variant, but the description never explicitly says when to prefer it over x402_check or bazaar_check. The billing rules (any HTTP answer billed; bad input, blocked hosts, timeouts not) do help decide whether a probe is worth issuing, which lifts it above a bare 2.

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