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check_return

Answer one question: can this specific product actually be returned? BEST RESULTS: send the product page you already have as page_text (or page_html) along with product_url — your browser renders JavaScript and is not blocked by retailers, so this works on any store and is faster. Without it we fetch the page ourselves and reach the policy for about 1 in 3 US retailers (17 of 50 measured 2026-08-28; mostly Shopify and direct-to-consumer brands — large retailers and marketplaces block server-side reads). You get a verified verdict — YES / YES_WITH_CONDITIONS / NO / UNKNOWN — with the exact policy clause quoted verbatim, source URL, return window/deadline, fees and a confidence score. Never invents: returns UNKNOWN instead of guessing, and UNKNOWN is free.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
reasonNo
merchantNo
page_htmlNoRECOMMENDED (alternative to page_text). Raw HTML of the same page. Slightly better than page_text: we can also read structured data (JSON-LD) from it.
page_textNoRECOMMENDED. Plain text of the product or returns page you already have open. We verify against this instead of fetching: works on any store, no blocking, no JavaScript problem, and faster. Still never invents: no verifiable clause -> UNKNOWN (free).
product_urlYesThe product page URL (http/https).
seller_nameNo
buyer_countryYesISO 3166-1 alpha-2, e.g. 'US'.
delivery_dateNoYYYY-MM-DD (optional; preferred for the deadline).
purchase_dateNoYYYY-MM-DD (optional).
item_conditionNo
page_source_urlNoURL of the supplied page_text/page_html when different from product_url. Caller-declared provenance; not independently fetched.
payment_signatureNoOPTIONAL. x402 payment authorization, base64 — the same envelope the PAYMENT-SIGNATURE header carries over HTTP. Use it to pay per call with no account and no signup. How: call once without it; if the free trial is exhausted you get the payment terms in structuredContent (x402Version, accepts[]); sign that authorization and call again with payment_signature set. Terms are also published at /.well-known/x402. UNKNOWN verdicts are never settled: the authorization simply expires unused.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed1 schema field changed
    • addedInput schema / properties / page_source_url
      Added value: +{
      +  "description": "URL of the supplied page_text/page_html when different from product_url. Caller-declared provenance; not independently fetched.",
      +  "type": "string"
      +}
  2. Changed1 schema field changed
    • addedInput schema / properties / payment_signature
      Added value: +{
      +  "description": "OPTIONAL. x402 payment authorization, base64 — the same envelope the PAYMENT-SIGNATURE header carries over HTTP. Use it to pay per call with no account and no signup. How: call once without it; if the free trial is exhausted you get the payment terms in structuredContent (x402Version, accepts[]); sign that authorization and call again with payment_signature set. Terms are also published at /.well-known/x402. UNKNOWN verdicts are never settled: the authorization simply expires unused.",
      +  "type": "string"
      +}
  3. Changed2 schema fields changed
    • changedInput schema / properties / page_html / description
      Previous value: -"Optional: raw HTML of the page you already have. If provided, ReturnCheck verifies against it instead of fetching — best coverage, bypasses sites that block server-side reads. Still never invents: no verifiable clause -> UNKNOWN."New value: +"RECOMMENDED (alternative to page_text). Raw HTML of the same page. Slightly better than page_text: we can also read structured data (JSON-LD) from it."
    • changedInput schema / properties / page_text / description
      Previous value: -"Optional: plain text of the page (alternative to page_html)."New value: +"RECOMMENDED. Plain text of the product or returns page you already have open. We verify against this instead of fetching: works on any store, no blocking, no JavaScript problem, and faster. Still never invents: no verifiable clause -> UNKNOWN (free)."
  4. Changed2 schema fields changed
    • addedInput schema / properties / page_html
      Added value: +{
      +  "description": "Optional: raw HTML of the page you already have. If provided, ReturnCheck verifies against it instead of fetching — best coverage, bypasses sites that block server-side reads. Still never invents: no verifiable clause -> UNKNOWN.",
      +  "type": "string"
      +}
    • addedInput schema / properties / page_text
      Added value: +{
      +  "description": "Optional: plain text of the page (alternative to page_html).",
      +  "type": "string"
      +}
  5. First observed

TDQS

A4.5/5.0
Behavior5/5

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

With no annotations, the description carries the full burden and does so well: it discloses the verification behavior (quotes the exact clause verbatim, cites source URL, window/deadline, fees, confidence score), the anti-hallucination contract ('Never invents: returns UNKNOWN instead of guessing'), the cost caveat ('UNKNOWN is free'), and the measured server-side fetch hit rate. It also details the x402 payment path (call once free, read terms from structuredContent, re-call with payment_signature, and that UNKNOWN verdicts are never settled).

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 core question and the primary usage recommendation are front-loaded in the first sentence, and each sentence adds distinct information (fallback reliability, verdict format, no-guessing guarantee, payment mechanics). It is dense and longer than typical, with the payment details occupying substantial space, but no sentence is pure filler.

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?

With no annotations and no output schema, the description compensates well by specifying what a result contains (verdict, verbatim clause, source URL, deadline, fees, confidence) and how failure is signaled (UNKNOWN, free). The remaining gap is that the role of the half-dozen optional inputs (reason, seller_name, item_condition, dates) in shaping the verdict is never explained.

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

Parameters4/5

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

Schema coverage is 67%, and the description adds real meaning for the most consequential params: page_text vs page_html tradeoffs (HTML allows JSON-LD structured data), page_source_url as caller-declared, unfetched provenance, and the full payment_signature workflow. However, several optional params (reason, merchant, seller_name, item_condition, dates) are neither described here nor in the schema, leaving their effect on the verdict unstated.

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?

The opening sentence states a precise, single-purpose question: 'can this specific product actually be returned?' and the description immediately enumerates the exact output verdicts (YES / YES_WITH_CONDITIONS / NO / UNKNOWN). There are no sibling tools to differentiate from, and the scope (one product, returns eligibility, with quoted policy clause) is unambiguous.

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

Usage Guidelines4/5

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

It gives explicit optimal-use guidance ('BEST RESULTS: send the product page you already have as page_text (or page_html) along with product_url') and explains the consequence of not doing so (server-side fetch reaches policy for only ~1 in 3 US retailers, with the measured date and which retailer types are blocked). No alternatives or exclusions are named because none exist, so this is clear context rather than full when/when-not routing.

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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