Agent Decision & Evidence Tools (MCP + x402)

Autonomous payment gate

must_verify_before_pay

Read-only

Return allow or deny before an agent pays a counterparty, using sanctions screening, live VIES validation and IBAN structure evidence. Deny is the default and the decision carries a signed receipt.

Input Schema

TableJSON Schema

Name	Required	Default
`amount`	No
`country`	No
`currency`	No	EUR
`payee_vat`	Yes
`payee_iban`	Yes
`payee_name`	Yes

Output Schema

TableJSON Schema

Name	Required	Description
`tool`	No
`error`	No
`payee`	No
`amount`	No
`checks`	No
`detail`	No
`policy`	No
`allowed`	No
`charged`	No	When present on an error, false means the failed result is uncharged.
`message`	No
`missing`	No
`reasons`	No
`receipt`	No
`settled`	No	When present on an error, false means no settlement occurred.
`unknown`	No
`accepted`	No
`currency`	No
`decision`	No
`retryable`	No
`error_code`	No
`extensions`	No
`risk_level`	No
`status_code`	No
`did_you_mean`	No
`missing_checks`	No
`verify_offline`	No
`partial_evidence`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed14 schema fields changedSep 6, 2026

addedInput schema / additionalProperties
```
Added value: +false
```
addedInput schema / properties / amount / minimum
```
Added value: +0
```
removedInput schema / properties / amount / title
```
Removed value: -"Amount"
```
removedInput schema / properties / country / title
```
Removed value: -"Country"
```
removedInput schema / properties / currency / title
```
Removed value: -"Currency"
```
removedInput schema / properties / payee_iban / default
```
Removed value: -""
```
removedInput schema / properties / payee_iban / title
```
Removed value: -"Payee Iban"
```
removedInput schema / properties / payee_name / default
```
Removed value: -""
```
removedInput schema / properties / payee_name / title
```
Removed value: -"Payee Name"
```
removedInput schema / properties / payee_vat / default
```
Removed value: -""
```
removedInput schema / properties / payee_vat / title
```
Removed value: -"Payee Vat"
```

addedInput schema / required

Added value: +[
+  "payee_name",
+  "payee_vat",
+  "payee_iban"
+]

removedInput schema / title

Removed value: -"must_verify_before_pay_toolArguments"

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "anyOf": [
+    {
+      "required": [
+        "decision",
+        "allowed",
+        "reasons",
+        "payee",
+        "amount",
+        "currency",
+        "risk_level",
+        "checks",
+        "detail",
+        "policy",
+        "verify_offline",
+        "receipt",
+        "extensions"
+      ]
+    },
+    {
+      "required": [
+        "error"
+      ]
+    }
+  ],
+  "description": "Structured result contract for must_verify_before_pay. A success satisfies the documented success branch. A domain or tool error includes error and is not a successful settlement; unpaid x402 requirements are carried by the transport wrapper.",
+  "properties": {
+    "accepted": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "allowed": {
+      "type": "boolean"
+    },
+    "amount": {
+      "type": "number"
+    },
+    "charged": {
+      "description": "When present on an error, false means the failed result is uncharged.",
+      "type": "boolean"
+    },
+    "checks": {
+      "items": {},
+      "type": "array"
+    },
+    "currency": {
+      "type": "string"
+    },
+    "decision": {
+      "enum": [
+        "allow",
+        "deny"
+      ],
+      "type": "string"
+    },
+    "detail": {
+      "additionalProperties": true,
+      "type": "object"
+    },
+    "did_you_mean": {
+      "additionalProperties": true,
+      "type": [
+        "object",
+        "null"
+      ]
+    },
+    "error": {
+      "oneOf": [
+        {
+          "type": "string"
+        },
+        {
+          "additionalProperties": true,
+          "properties": {
+            "code": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "message": {
+              "type": "string"
+            },
+            "param": {
+              "type": [
+                "string",
+                "null"
+              ]
+            },
+            "type": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "message"
+          ],
+          "type": "object"
+        }
+      ]
+    },
+    "error_code": {
+      "type": "string"
+    },
+    "extensions": {
+      "additionalProperties": true,
+      "properties": {
+        "delivery-receipt": {
+          "additionalProperties": true,
+          "properties": {
+            "how_to_verify": {
+              "type": "string"
+            },
+            "issued_at": {
+              "format": "date-time",
+              "type": "string"
+            },
+            "issuer": {
+              "type": "string"
+            },
+            "issuer_key": {
+              "type": "string"
+            },
+            "key_id": {
+              "type": "string"
+            },
+            "result_hash": {
+              "type": "string"
+            },
+            "service": {
+              "type": "string"
+            },
+            "signature": {
+              "type": "string"
+            },
+            "signed_message": {
+              "type": "string"
+            },
+            "standard": {
+              "const": "eucompliance-receipt/2",
+              "type": "string"
+            },
+            "subject": {
+              "type": "string"
+            },
+            "valid_until": {
+              "format": "date-time",
+              "type": "string"
+            },
+            "verify_url": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "standard",
+            "service",
+            "subject",
+            "result_hash",
+            "issued_at",
+            "valid_until",
+            "issuer",
+            "issuer_key",
+            "key_id",
+            "verify_url",
+            "how_to_verify",
+            "signature",
+            "signed_message"
+          ],
+          "type": "object"
+        }
+      },
+      "required": [
+        "delivery-receipt"
+      ],
+      "type": "object"
+    },
+    "message": {
+      "type": "string"
+    },
+    "missing": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "missing_checks": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "partial_evidence": {
+      "additionalProperties": true,
+      "type": "object"
+    },
+    "payee": {
+      "additionalProperties": true,
+      "type": "object"
+    },
+    "policy": {
+      "type": "string"
+    },
+    "reasons": {
+      "items": {},
+      "type": "array"
+    },
+    "receipt": {
+      "additionalProperties": true,
+      "properties": {
+        "how_to_verify": {
+          "type": "string"
+        },
+        "issued_at": {
+          "format": "date-time",
+          "type": "string"
+        },
+        "issuer": {
+          "type": "string"
+        },
+        "issuer_key": {
+          "type": "string"
+        },
+        "key_id": {
+          "type": "string"
+        },
+        "result_hash": {
+          "type": "string"
+        },
+        "service": {
+          "type": "string"
+        },
+        "signature": {
+          "type": "string"
+        },
+        "signed_message": {
+          "type": "string"
+        },
+        "standard": {
+          "const": "eucompliance-receipt/2",
+          "type": "string"
+        },
+        "subject": {
+          "type": "string"
+        },
+        "valid_until": {
+          "format": "date-time",
+          "type": "string"
+        },
+        "verify_url": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "standard",
+        "service",
+        "subject",
+        "result_hash",
+        "issued_at",
+        "valid_until",
+        "issuer",
+        "issuer_key",
+        "key_id",
+        "verify_url",
+        "how_to_verify",
+        "signature",
+        "signed_message"
+      ],
+      "type": "object"
+    },
+    "retryable": {
+      "type": "boolean"
+    },
+    "risk_level": {
+      "type": "string"
+    },
+    "settled": {
+      "description": "When present on an error, false means no settlement occurred.",
+      "type": "boolean"
+    },
+    "status_code": {
+      "type": "integer"
+    },
+    "tool": {
+      "type": "string"
+    },
+    "unknown": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "verify_offline": {
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

AddedJul 31, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already mark the tool as read-only and non-destructive. The description adds meaningful behavior beyond that: 'Deny is the default' and the decision carries a signed receipt, plus the 'live' nature of VIES validation. It does not contradict 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?

Two sentences, zero filler, with the core result ('allow or deny') front-loaded before supporting detail. Every clause adds information.

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?

The core purpose and required inputs are clear, and the output schema can carry return-value details, but optional parameters remain ambiguous and no alternative-tool routing is provided. Adequate for simple calls, yet incomplete for informed use of all six parameters.

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?

With 0% schema description coverage, the description must compensate for all parameters. It implicitly covers payee_name, payee_vat, and payee_iban through the screening/VIES/IBAN checks, but amount, country, and currency are left entirely unexplained.

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 description is specific: it returns an allow/deny decision before payment, backed by sanctions screening, VIES validation and IBAN evidence. This clearly separates it from sibling validators like screen_sanctions_eu, validate_vat, and validate_iban by presenting it as a composite gate.

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 explicitly states the trigger condition: 'before an agent pays a counterparty'. It does not name alternatives or exclusions, but the context is clear enough for an agent to select it over single-check tools.

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

All Agent Decision & Evidence Tools (MCP + x402) tools Inspect

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