get_listing_proof

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

With no annotations, the description carries the full burden and does substantial work: it discloses that the tool is free, that it actively probes the paid endpoint, that it fetches and parses the agent's openapi.json, that it compares advertised price to the live challenge, and that it returns PASS/DRIFT/BROKEN verdicts with a 0.95 match threshold. It stops short of stating whether the tool is strictly read-only, how long a probe takes, or what happens when an agent has no settled usage (only 'when usage exists' is hinted).

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?

The core purpose is front-loaded, but the body is a single dense run-on sentence dense with parenthetical asides and marketing framing ('invention #4033', '[FREE]') that dilute scanability. The text terminates mid-word ('with a summa'), so the definition is visibly truncated and loses its closing information.

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 no-annotation, no-output-schema tool, the description explains the three proof dimensions and the verdict vocabulary well, which is the hard part. However, the truncation removes the description of the full-board/summary response, and nothing is said about the shape of per-agent results beyond the verdict labels, leaving the agent guessing at the return payload.

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 0% for the single slug parameter, so the description must compensate, and it largely does: it gives an example value ('cipher') and explains the empty-string semantics ('leave empty for the full board'). The sentence describing what the full-board response contains is cut off, leaving the aggregate mode's output under-specified.

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 names a specific verb+resource combination (a three-side capability proof for AgentPayStore marketplace listings) and defines each side concretely: LIVE = live x402 402 challenge, SPEC = openapi.json parses with x-payment-required and matching price, LEDGER = observed response keys match advertised shape at match_score >= 0.95. It does not differentiate itself from adjacent siblings such as check_x402_endpoint, marketplace_check_endpoint, or get_capability_snapshot, which overlap in subject matter.

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 slug instruction ('Pass a slug ... to prove one agent, or leave empty for the full board'), which tells the agent how to scope a call but not when to prefer this tool over the many sibling verification tools. No exclusions, prerequisites, or named alternatives are given, so the agent must infer fit from the name and the LIVE/SPEC/LEDGER breakdown.

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