x402-data-gateway

Preflight x402 and MPP Offer

payment_offer_preflight

Compare x402 and MPP payment challenges, terms, and seller-declared JSON success-response readiness for one exact public HTTPS GET route before buyer authorization, including URL and realm binding, expiry, cross-protocol economic parity, and exact-route OpenAPI evidence. Use agent_discoverability_audit instead when you need to know whether catalogs rank or expose a service. This tool uses no target credential, signature, or target payment, follows no redirect, never reads the paid target body, and reads only the same-origin public OpenAPI document under a strict size cap. A seller declaration is advisory and does not establish runtime validity, seller trust, utility, or settlement reliability. Payment challenge and credentials are bound to GET https://agents.samedaydesk.com/commerce/payment-offer-preflight, not mcp://. Retry the identical authorized arguments and credential.

Input Schema

Name	Required	Description	Default
`url`	Yes	Exact public HTTPS GET route whose unpaid x402 and MPP challenge headers and same-origin OpenAPI success-response declaration should be inspected before buyer authorization. Credential-like query keys, fragments, unresolved parameters, local hosts, redirects, and non-public IPs are rejected.
`catalog`	No	Optional caller-supplied catalog candidate. When present, the tool compares it with every live unsigned offer across request, protocol, amount, network, asset, recipient, and expiry.

Output Schema

Name	Required	Description	Default
`ok`	Yes
`offers`	Yes
`parity`	Yes
`target`	Yes
`product`	Yes
`version`	Yes
`boundary`	Yes
`decision`	Yes
`findings`	Yes
`checkedAt`	Yes
`protocols`	Yes
`offerCount`	Yes
`catalogCoherence`	Yes
`responseContract`	Yes
`responseContractAcquisition`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedAug 20, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "boundary": {
+      "additionalProperties": false,
+      "properties": {
+        "claim": {
+          "type": "string"
+        },
+        "credentialsUsed": {
+          "const": false,
+          "type": "boolean"
+        },
+        "openApiDocumentRead": {
+          "type": "boolean"
+        },
+        "paymentSent": {
+          "const": false,
+          "type": "boolean"
+        },
+        "paymentSigned": {
+          "const": false,
+          "type": "boolean"
+        },
+        "redirectsFollowed": {
+          "const": false,
+          "type": "boolean"
+        },
+        "targetResponseBodyRead": {
+          "const": false,
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "credentialsUsed",
+        "paymentSigned",
+        "paymentSent",
+        "targetResponseBodyRead",
+        "openApiDocumentRead",
+        "redirectsFollowed",
+        "claim"
+      ],
+      "type": "object"
+    },
+    "catalogCoherence": {
+      "items": {
+        "additionalProperties": true,
+        "properties": {
+          "decision": {
+            "enum": [
+              "coherent",
+              "partial",
+              "drifted"
+            ],
+            "type": "string"
+          }
+        },
+        "required": [
+          "decision"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "checkedAt": {
+      "format": "date-time",
+      "type": "string"
+    },
+    "decision": {
+      "enum": [
+        "parseable_offer",
+        "review_required",
+        "no_parseable_offer"
+      ],
+      "type": "string"
+    },
+    "findings": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "code": {
+            "type": "string"
+          },
+          "message": {
+            "type": "string"
+          },
+          "severity": {
+            "enum": [
+              "error",
+              "warning"
+            ],
+            "type": "string"
+          }
+        },
+        "required": [
+          "severity",
+          "code",
+          "message"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "offerCount": {
+      "minimum": 0,
+      "type": "integer"
+    },
+    "offers": {
+      "items": {
+        "anyOf": [
+          {
+            "additionalProperties": false,
+            "properties": {
+              "amountAtomic": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "amountDisplay": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "asset": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "decimals": {
+                "anyOf": [
+                  {
+                    "type": "integer"
+                  },
+                  {
+                    "type": "null"
+                  }
+                ]
+              },
+              "expiresAt": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "intent": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "network": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "protocol": {
+                "const": "x402",
+                "type": "string"
+              },
+              "recipient": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "scheme": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "valid": {
+                "type": "boolean"
+              }
+            },
+            "required": [
+              "protocol",
+              "scheme",
+              "intent",
+              "network",
+              "asset",
+              "amountAtomic",
+              "decimals",
+              "amountDisplay",
+              "recipient",
+              "expiresAt",
+              "valid"
+            ],
+            "type": "object"
+          },
+          {
+            "additionalProperties": false,
+            "properties": {
+              "amountAtomic": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/amountAtomic"
+              },
+              "amountDisplay": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/amountDisplay"
+              },
+              "asset": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/asset"
+              },
+              "credentialTypes": {
+                "items": {
+                  "type": "string"
+                },
+                "type": "array"
+              },
+              "decimals": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/decimals"
+              },
+              "expiresAt": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/expiresAt"
+              },
+              "intent": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/intent"
+              },
+              "network": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/network"
+              },
+              "protocol": {
+                "const": "mpp",
+                "type": "string"
+              },
+              "realm": {
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
+              "recipient": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/recipient"
+              },
+              "scheme": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/scheme"
+              },
+              "valid": {
+                "$ref": "#/properties/offers/items/anyOf/0/properties/valid"
+              }
+            },
+            "required": [
+              "protocol",
+              "scheme",
+              "intent",
+              "network",
+              "asset",
+              "amountAtomic",
+              "decimals",
+              "amountDisplay",
+              "recipient",
+              "expiresAt",
+              "valid",
+              "realm",
+              "credentialTypes"
+            ],
+            "type": "object"
+          }
+        ]
+      },
+      "type": "array"
+    },
+    "ok": {
+      "const": true,
+      "type": "boolean"
+    },
+    "parity": {
+      "additionalProperties": false,
+      "properties": {
+        "compared": {
+          "type": "boolean"
+        },
+        "consistent": {
+          "type": [
+            "boolean",
+            "null"
+          ]
+        },
+        "driftFields": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        }
+      },
+      "required": [
+        "compared",
+        "consistent",
+        "driftFields"
+      ],
+      "type": "object"
+    },
+    "product": {
+      "const": "samedaydesk-payment-offer-preflight",
+      "type": "string"
+    },
+    "protocols": {
+      "items": {
+        "enum": [
+          "mpp",
+          "x402"
+        ],
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "responseContract": {
+      "additionalProperties": true,
+      "properties": {
+        "decision": {
+          "enum": [
+            "admissible",
+            "partial",
+            "absent",
+            "invalid"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "decision"
+      ],
+      "type": "object"
+    },
+    "responseContractAcquisition": {
+      "additionalProperties": false,
+      "properties": {
+        "attempted": {
+          "const": true,
+          "type": "boolean"
+        },
+        "credentialsUsed": {
+          "const": false,
+          "type": "boolean"
+        },
+        "documentRead": {
+          "type": "boolean"
+        },
+        "maxBytes": {
+          "exclusiveMinimum": 0,
+          "type": "integer"
+        },
+        "path": {
+          "const": "/openapi.json",
+          "type": "string"
+        },
+        "redirectsFollowed": {
+          "const": false,
+          "type": "boolean"
+        },
+        "sameOrigin": {
+          "const": true,
+          "type": "boolean"
+        },
+        "targetResponseBodyRead": {
+          "const": false,
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "attempted",
+        "sameOrigin",
+        "path",
+        "maxBytes",
+        "documentRead",
+        "targetResponseBodyRead",
+        "credentialsUsed",
+        "redirectsFollowed"
+      ],
+      "type": "object"
+    },
+    "target": {
+      "additionalProperties": false,
+      "properties": {
+        "httpStatus": {
+          "type": "integer"
+        },
+        "method": {
+          "const": "GET",
+          "type": "string"
+        },
+        "url": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "method",
+        "url",
+        "httpStatus"
+      ],
+      "type": "object"
+    },
+    "version": {
+      "const": "1.2.0",
+      "type": "string"
+    }
+  },
+  "required": [
+    "ok",
+    "product",
+    "version",
+    "checkedAt",
+    "target",
+    "decision",
+    "protocols",
+    "offerCount",
+    "offers",
+    "parity",
+    "catalogCoherence",
+    "responseContract",
+    "responseContractAcquisition",
+    "findings",
+    "boundary"
+  ],
+  "type": "object"
+}

Changed1 schema field changedAug 12, 2026

changedInput schema / properties / url / description

Previous value: -"Exact public HTTPS GET route whose unpaid x402 and MPP challenge headers should be inspected before buyer authorization. Credential-like query keys, fragments, unresolved parameters, local hosts, redirects, and non-public IPs are rejected."New value: +"Exact public HTTPS GET route whose unpaid x402 and MPP challenge headers and same-origin OpenAPI success-response declaration should be inspected before buyer authorization. Credential-like query keys, fragments, unresolved parameters, local hosts, redirects, and non-public IPs are rejected."

Changed1 schema field changedAug 12, 2026

addedInput schema / properties / catalog

Added value: +{
+  "additionalProperties": false,
+  "description": "Optional caller-supplied catalog candidate. When present, the tool compares it with every live unsigned offer across request, protocol, amount, network, asset, recipient, and expiry.",
+  "properties": {
+    "amountAtomic": {
+      "description": "Optional advertised price in atomic currency units.",
+      "pattern": "^(?:0|[1-9][0-9]{0,77})$",
+      "type": "string"
+    },
+    "asset": {
+      "description": "Optional advertised currency or asset identifier.",
+      "maxLength": 200,
+      "minLength": 1,
+      "type": "string"
+    },
+    "expiresAt": {
+      "description": "Optional advertised offer expiry.",
+      "format": "date-time",
+      "type": "string"
+    },
+    "method": {
+      "const": "GET",
+      "description": "Catalog request method. The current product inspects exact GET routes.",
+      "type": "string"
+    },
+    "network": {
+      "description": "Optional advertised network identifier.",
+      "maxLength": 200,
+      "minLength": 1,
+      "type": "string"
+    },
+    "protocol": {
+      "description": "Optional advertised payment protocol.",
+      "enum": [
+        "x402",
+        "mpp"
+      ],
+      "type": "string"
+    },
+    "recipient": {
+      "description": "Optional advertised payment recipient.",
+      "maxLength": 200,
+      "minLength": 1,
+      "type": "string"
+    },
+    "source": {
+      "description": "Public catalog or registry name.",
+      "maxLength": 128,
+      "minLength": 1,
+      "type": "string"
+    },
+    "url": {
+      "description": "Exact catalog candidate URL, including all non-secret query values.",
+      "format": "uri",
+      "maxLength": 2048,
+      "type": "string"
+    }
+  },
+  "required": [
+    "source",
+    "method",
+    "url"
+  ],
+  "type": "object"
+}

AddedAug 10, 2026

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 discharges it: no target credential, signature, or payment is used; no redirects followed; paid target body never read; only the same-origin public OpenAPI document is fetched under a strict size cap. It also warns that a seller declaration is advisory and does not establish runtime validity, trust, utility, or settlement reliability.

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

Conciseness3/5

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

The purpose is front-loaded and every claim is informative, but the payload arrives as one dense four-sentence block with heavy clause stacking and redundant restatement of URL/route binding. It is information-rich but not well-structured or skimmable.

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?

An output schema exists, so return values need no explanation, and the absence of annotations is fully compensated by explicit disclosure of what the tool does not touch (credentials, signatures, redirects, target body) and the retry guidance. Nothing needed to call it correctly is missing.

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 both the `url` and nested `catalog` object fields are already fully documented in the schema. The description only restates the exact-route scoping already covered by the `url` schema description, so it adds little beyond the structured fields — baseline 3 applies.

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 scope: compare x402 and MPP challenges, terms, and seller-declared JSON success-response readiness for one exact public HTTPS GET route. It explicitly distinguishes itself from the sibling `agent_discoverability_audit` by naming the different question that tool answers.

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 an explicit when-to-use ('before buyer authorization') and an explicit alternative with its selecting condition ('use `agent_discoverability_audit` instead when you need to know whether catalogs rank or expose a service'). Nothing is left to inference for tool selection.

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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