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

quote_diff_diff

$0.01 USDC on Solana per pair - the payment buys one signed quote-pair diff: the two captured 402 challenges you submit are normalised (header-carried and body-carried forms unified) and compared across eight payment-term fields - price, asset, network, payTo, token account, timeout, description, memo presence/form - each graded SAME, CHANGED, PRESENT-ONLY-IN-FIRST, PRESENT-ONLY-IN-SECOND, or UNPARSEABLE. No composite score. Submitted challenges are processed in memory only and are never stored.

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": {
      "first": "<first>",
      "second": "<second>"
    },
    "name": "quote_diff_diff"
  }
}

Input Schema

Name	Required	Description	Default
`first`	Yes	One captured 402 challenge in the published submission form: {status?, body (object, JSON string, or null), payment_required_header (base64 string or null)}; at least one carrier present. Processed in memory only, never stored.
`second`	Yes	One captured 402 challenge in the published submission form: {status?, body (object, JSON string, or null), payment_required_header (base64 string or null)}; at least one carrier present. Processed in memory only, never stored.

Schema Changelog

Changes observed during successful MCP inspections.

AddedNov 3, 2026

TDQS

A3.9/5.0

Behavior4/5

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

With no annotations, the description carries the full burden and does well: it discloses the exact cost and chain ($0.01 USDC on Solana per pair), that challenges are processed in memory only and never stored, that there is no composite score, and which normalisation is applied to header- vs body-carried forms. It stops short of describing the signed response envelope or what a paid call failure/refund looks like.

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?

One dense sentence plus two short follow-ups, front-loaded with the price and the core action. The eight-field enumeration is long but earns its place by defining the comparison surface; only minor trimming would be possible.

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

Completeness4/5

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

For a two-parameter tool with no annotations and no output schema, the description covers the essentials: inputs required, normalisation, graded output vocabulary, absence of a composite score, and data-handling policy. The main remaining gap is the shape of the returned signed diff object, which with no output schema the agent must discover empirically.

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

Parameters3/5

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

Schema description coverage is 100%, so the baseline is 3. The description does add some meaning beyond the schema by explaining that header-carried and body-carried inputs are unified before comparison, which clarifies why two differently-shaped captures can be diffed, but it adds nothing about ordering semantics or the optional status field.

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

Purpose5/5

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

States a precise verb and resource: the two submitted 402 challenges are normalised and compared field-by-field, with results graded on a named five-value scale. This is clearly distinguishable from the sibling quote_diff_criteria (rules) and quote_diff_precheck (validation) tools, which do not produce a diff.

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

Usage Guidelines3/5

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

Usage is implied rather than stated: 'the two captured 402 challenges you submit' tells the agent it needs two captured challenges, and the price line frames this as a paid operation, but there is no explicit when-to-use vs. quote_diff_precheck/quote_diff_criteria guidance and no stated precondition (e.g. run precheck first).

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

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

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