ExchangeRebel — pay-per-call APIs for AI agents (x402 on Solana)

listing_check_check

$0.02 USDC on Solana per op - the payment buys one signed listing-vs-live consistency grade: the service fetches the listing's own URL live and grades url, method, resource, price, asset and network field by field (CONSISTENT / INCONSISTENT / PARTIALLY-OBSERVABLE / UNREACHABLE).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "listing": "<listing>"
    },
    "name": "listing_check_check"
  }
}

Input Schema

Name	Required	Description	Default
`op`	No
`listing`	Yes	The listing under check, in the op's published form (check: url, method, network, asset, price_micro; example: example_input + input_schema; promise: max_timeout_seconds + declared_delivery_seconds).

Schema Changelog

Changes observed during successful MCP inspections.

AddedNov 3, 2026

TDQS

B3.2/5.0

Behavior4/5

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

No annotations are provided, so the description carries the full burden. It discloses the paid nature of the operation ($0.02 USDC on Solana per op), that the service fetches the listing's URL live, that grading is field by field, and that results are one of four named categories. It still omits authentication, timeout, and payment-execution details, but it provides substantial behavioral context beyond the schema.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is one dense sentence with no obvious filler, and it covers pricing, live fetching, field-by-field grading, and possible outcomes. The price is front-loaded before the tool's purpose, which is slightly less effective than leading with the action, but the sentence remains compact and readable.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the nested listing object, the missing output schema, and the absence of annotations, the description does a reasonable job explaining what is graded and what result categories exist. However, it leaves the op parameter undefined and does not clarify payment flow, auth requirements, or failure behavior. That is enough for partial understanding but not complete readiness to invoke correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 50%, and the op parameter has no schema description at all. The description mentions 'per op' and 'the op's published form' but never explains what op means or what values it accepts. The listing field list repeats the schema description rather than adding meaning, leaving parameter semantics under-specified.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific action: it fetches the listing's own URL live and grades url, method, resource, price, asset, and network field by field. That is a clear verb-plus-resource purpose. It does not distinguish itself from nearby siblings such as listing_check_precheck, listing_check_criteria, or listing_check_example, so it falls short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives no explicit when-to-use or when-not-to-use guidance, and it does not route the agent among the many listing_check_* siblings. Usage is only implied by the statement that it fetches and grades a listing. With a precheck, criteria, example, bazaar, and promise variant present, this is a meaningful omission.

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

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