Genesis402

Check email or domain deliverability

genesis402_email_check

Check an email address or domain for deliverability and trust before accepting a signup or inbound sender. Returns MX, SPF/DMARC, disposable-domain flag, and a 0-5 trust score via DNS-only lookup.

Instructions

Paid ($0.002 USDC). Deliverability and trust check for an email address or domain. Use to vet a signup email or an inbound sender. For the domain's registration age and registrar use genesis402_whois. Returns whether it can receive mail (MX), the hosting provider, SPF and DMARC records and policy, a disposable-domain flag and a 0-5 trust score. DNS-only: no SMTP probe, no email sent, the mailbox is never contacted. Payment: call once without payment_signature to get the exact price quote (nothing is charged or signed), then call again with the signed payment to receive the result and settlement details.

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": {
      "email_or_domain": "<email_or_domain>"
    },
    "name": "genesis402_email_check"
  }
}

Input Schema

Name	Required	Description	Default
`email_or_domain`	Yes	A full email address (user@domain.com) or a bare domain (domain.com), without scheme or path.
`payment_signature`	No	Optional. An x402 v2 payment you signed for this call's quote (the PAYMENT-SIGNATURE header value). Omit to get the price quote first; nothing is charged without it.

Output Schema

Name	Required	Description
`mode`	Yes	QUOTE_ONLY: price quote only, nothing signed or charged. PAID: the call was paid and result holds the data. FREE: the endpoint answered without payment.
`paid`	Yes	true only when a payment was settled for this call.
`price`	No	The Base USDC quote. Present on QUOTE_ONLY and on PAID calls made by a local payer; null when the rail offered no Base USDC lane or the caller signed the payment.
`result`	No	PAID or FREE: the endpoint's JSON result.
`resource`	No	QUOTE_ONLY: the full URL of the paid resource.
`how_to_pay`	No	QUOTE_ONLY: how to sign and resend the call.
`settlement`	No	PAID: decoded PAYMENT-RESPONSE settlement (transaction hash, network, payer), or null if the rail sent none.
`what_you_get`	No	QUOTE_ONLY: the rail's description of what the payment buys.
`payment_required_b64`	No	QUOTE_ONLY: the raw base64 PAYMENT-REQUIRED header, to sign with any x402 v2 client.
`also_accepted_networks`	No	QUOTE_ONLY: every network the 402 challenge accepts.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.3.4Sep 29, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "also_accepted_networks": {
+      "description": "QUOTE_ONLY: every network the 402 challenge accepts.",
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "how_to_pay": {
+      "description": "QUOTE_ONLY: how to sign and resend the call.",
+      "type": "string"
+    },
+    "mode": {
+      "description": "QUOTE_ONLY: price quote only, nothing signed or charged. PAID: the call was paid and result holds the data. FREE: the endpoint answered without payment.",
+      "enum": [
+        "QUOTE_ONLY",
+        "PAID",
+        "FREE"
+      ],
+      "type": "string"
+    },
+    "paid": {
+      "description": "true only when a payment was settled for this call.",
+      "type": "boolean"
+    },
+    "payment_required_b64": {
+      "description": "QUOTE_ONLY: the raw base64 PAYMENT-REQUIRED header, to sign with any x402 v2 client.",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "price": {
+      "anyOf": [
+        {
+          "additionalProperties": false,
+          "properties": {
+            "atomic": {
+              "description": "Price in USDC atomic units (6 decimals), as a decimal string.",
+              "type": "string"
+            },
+            "network": {
+              "description": "CAIP-2 network id of the lane, eip155:8453 (Base).",
+              "type": "string"
+            },
+            "payTo": {
+              "description": "Address the payment settles to.",
+              "type": "string"
+            },
+            "usd": {
+              "description": "Price in US dollars.",
+              "type": "number"
+            }
+          },
+          "required": [
+            "atomic",
+            "usd",
+            "payTo",
+            "network"
+          ],
+          "type": "object"
+        },
+        {
+          "type": "null"
+        }
+      ],
+      "description": "The Base USDC quote. Present on QUOTE_ONLY and on PAID calls made by a local payer; null when the rail offered no Base USDC lane or the caller signed the payment."
+    },
+    "resource": {
+      "description": "QUOTE_ONLY: the full URL of the paid resource.",
+      "type": "string"
+    },
+    "result": {
+      "description": "PAID or FREE: the endpoint's JSON result."
+    },
+    "settlement": {
+      "description": "PAID: decoded PAYMENT-RESPONSE settlement (transaction hash, network, payer), or null if the rail sent none."
+    },
+    "what_you_get": {
+      "description": "QUOTE_ONLY: the rail's description of what the payment buys.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "mode",
+    "paid"
+  ],
+  "type": "object"
+}

Changed1 schema field changedv0.3.3Sep 29, 2026

changedInput schema / properties / email_or_domain / description

Previous value: -"A full email address (name@example.com) or a bare domain (example.com)."New value: +"A full email address (user@domain.com) or a bare domain (domain.com), without scheme or path."

Changed2 schema fields changedv0.3.2Sep 26, 2026

addedInput schema / properties / email_or_domain / description

Added value: +"A full email address (name@example.com) or a bare domain (example.com)."

changedInput schema / properties / payment_signature / description

Previous value: -"Optional. An x402 v2 payment you signed for this call's quote (the PAYMENT-SIGNATURE header value). Omit to get the price quote first."New value: +"Optional. An x402 v2 payment you signed for this call's quote (the PAYMENT-SIGNATURE header value). Omit to get the price quote first; nothing is charged without it."

First observedv0.3.1Sep 26, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Goes well beyond the sparse annotations (readOnlyHint=false, openWorldHint=true) by disclosing the DNS-only nature, that no SMTP probe or email is sent and the mailbox is never contacted, and the exact payment/settlement protocol. It also previews the returned signals (MX, provider, SPF/DMARC, disposable flag, 0-5 score). Nothing here contradicts the annotations.

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

Conciseness5/5

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

Front-loads the paid nature and the core purpose, then layers usage, sibling routing, return contents, safety scope, and payment flow. Dense but every sentence carries distinct information; no filler.

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

Completeness5/5

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

For a paid, open-world lookup with an output schema, the description supplies everything an agent needs: what it does, when to use it, the sibling alternative, the safety boundary, and the exact payment invocation sequence. Return values are additionally summarized even though an output schema exists.

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 100%, so the baseline is 3, and the description adds real meaning on top: it explains the quote-then-pay sequencing for payment_signature (call once with nothing charged to obtain the price, then again with the signed payment). It adds little to email_or_domain, which the schema already documents in full.

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 specific verb and resource — deliverability/trust check for an email address or domain — and explicitly routes the adjacent question (registration age, registrar) to the named sibling genesis402_whois. An agent can distinguish it from the other genesis402 tools without opening any schema.

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

Usage Guidelines5/5

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

Gives concrete usage contexts ('vet a signup email or an inbound sender') and names the alternative for the neighboring use case. The two-phase payment procedure is also spelled out, so the agent knows exactly how to invoke it correctly.

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