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Recursive JSON Schema Checking · Deterministic Validation

json_schema_check
Read-onlyIdempotent

Discover recursive JSON Schema checking for objects, arrays and scalars with exact JSON-path errors from ARN's bounded recursive JSON Schema subset. The supplied schema may combine type unions, required/properties, additionalProperties=false, items, enum/const, numeric bounds, string length or safe patterns, array bounds/uniqueness and property-count bounds; unsupported keywords fail closed. Prefer object_contract_check for a new simple top-level contract. This free MCP discovery call does not execute the advertised capability and does not charge; it returns the exact x402 endpoint, price and payment guide for execution.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
valueYesAny JSON value to validate.
schemaYesBounded recursive JSON Schema subset: type (including unions), required, properties, additionalProperties=false, items, enum, const, numeric bounds, string length/pattern, array length/uniqueness, and object property-count bounds. Unsupported keywords fail closed.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
priceYes
methodYesHTTP method for paid execution.
endpointYesCanonical absolute ARN HTTP URL to POST the same tool arguments to for paid execution.
protocolYesPayment protocol required by the HTTP execution endpoint.
instructionYesHow to execute the capability after receiving the payment requirement.
paymentGuideYesPublic setup guide with a working x402 v2 Base-mainnet client example.
paymentRequiredYesAlways true for paid ARN capabilities exposed over MCP.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed4 schema fields changed
    • changedOutput schema / properties / endpoint / description
      Previous value: -"ARN HTTP path to POST the same tool arguments to for paid execution."New value: +"Canonical absolute ARN HTTP URL to POST the same tool arguments to for paid execution."
    • addedOutput schema / properties / endpoint / format
      Added value: +"uri"
    • addedOutput schema / properties / method
      Added value: +{
      +  "const": "POST",
      +  "description": "HTTP method for paid execution.",
      +  "type": "string"
      +}
    • changedOutput schema / required
      Previous value: -[
      -  "paymentRequired",
      -  "protocol",
      -  "endpoint",
      -  "price",
      -  "paymentGuide",
      -  "instruction"
      -]New value: +[
      +  "paymentRequired",
      +  "protocol",
      +  "method",
      +  "endpoint",
      +  "price",
      +  "paymentGuide",
      +  "instruction"
      +]
  2. Changed6 schema fields changed
    • changedInput schema / description
      Previous value: -"Input for the bounded JSON-Schema-shaped compatibility checker."New value: +"Input for bounded recursive JSON Schema validation."
    • changedInput schema / properties / schema / description
      Previous value: -"Top-level contract definition. Only required, properties.<field>.type, and additionalProperties=false are evaluated."New value: +"Bounded recursive JSON Schema subset: type (including unions), required, properties, additionalProperties=false, items, enum, const, numeric bounds, string length/pattern, array length/uniqueness, and object property-count bounds. Unsupported keywords fail closed."
    • addedInput schema / properties / schema / maxProperties
      Added value: +1000
    • removedInput schema / properties / schema / properties
      Removed value: -{
      -  "additionalProperties": {
      -    "description": "Set false to report top-level fields not declared in properties.",
      -    "type": "boolean"
      -  },
      -  "properties": {
      -    "additionalProperties": {
      -      "additionalProperties": true,
      -      "properties": {
      -        "type": {
      -          "enum": [
      -            "null",
      -            "array",
      -            "object",
      -            "string",
      -            "number",
      -            "boolean"
      -          ],
      -          "type": "string"
      -        }
      -      },
      -      "type": "object"
      -    },
      -    "description": "Up to 1,000 top-level field definitions.",
      -    "maxProperties": 1000,
      -    "propertyNames": {
      -      "maxLength": 256,
      -      "minLength": 1
      -    },
      -    "type": "object"
      -  },
      -  "required": {
      -    "description": "Up to 1,000 unique top-level field names that must be present in value.",
      -    "items": {
      -      "maxLength": 256,
      -      "minLength": 1,
      -      "type": "string"
      -    },
      -    "maxItems": 1000,
      -    "type": "array",
      -    "uniqueItems": true
      -  }
      -}
    • changedInput schema / properties / value / description
      Previous value: -"JSON object to validate against the supported schema subset."New value: +"Any JSON value to validate."
    • removedInput schema / properties / value / type
      Removed value: -"object"
  3. Changed7 schema fields changed
    • changedInput schema / properties / schema / properties / properties / description
      Previous value: -"Top-level field definitions."New value: +"Up to 1,000 top-level field definitions."
    • addedInput schema / properties / schema / properties / properties / maxProperties
      Added value: +1000
    • addedInput schema / properties / schema / properties / properties / propertyNames
      Added value: +{
      +  "maxLength": 256,
      +  "minLength": 1
      +}
    • changedInput schema / properties / schema / properties / required / description
      Previous value: -"Top-level field names that must be present in value."New value: +"Up to 1,000 unique top-level field names that must be present in value."
    • addedInput schema / properties / schema / properties / required / items / maxLength
      Added value: +256
    • addedInput schema / properties / schema / properties / required / items / minLength
      Added value: +1
    • addedInput schema / properties / schema / properties / required / maxItems
      Added value: +1000
  4. Changed2 schema fields changed
    • addedOutput schema / properties / paymentGuide
      Added value: +{
      +  "description": "Public setup guide with a working x402 v2 Base-mainnet client example.",
      +  "format": "uri",
      +  "type": "string"
      +}
    • changedOutput schema / required
      Previous value: -[
      -  "paymentRequired",
      -  "protocol",
      -  "endpoint",
      -  "price",
      -  "instruction"
      -]New value: +[
      +  "paymentRequired",
      +  "protocol",
      +  "endpoint",
      +  "price",
      +  "paymentGuide",
      +  "instruction"
      +]
  5. Changed3 schema fields changed
    • changedInput schema / properties / schema / properties / additionalProperties / description
      Previous value: -"Set false to report top-level fields not declared in properties. Omitted or true allows them."New value: +"Set false to report top-level fields not declared in properties."
    • removedInput schema / properties / schema / properties / properties / additionalProperties / properties / type / description
      Removed value: -"Expected JSON type for this top-level field."
    • changedInput schema / properties / schema / properties / properties / description
      Previous value: -"Top-level field definitions. Each field may declare a JSON type; other JSON Schema keywords are ignored."New value: +"Top-level field definitions."
  6. Changed7 schema fields changed
    • addedInput schema / additionalProperties
      Added value: +false
    • addedInput schema / description
      Added value: +"Input for the bounded JSON-Schema-shaped compatibility checker."
    • addedInput schema / properties / schema / additionalProperties
      Added value: +true
    • addedInput schema / properties / schema / description
      Added value: +"Top-level contract definition. Only required, properties.<field>.type, and additionalProperties=false are evaluated."
    • addedInput schema / properties / schema / properties
      Added value: +{
      +  "additionalProperties": {
      +    "description": "Set false to report top-level fields not declared in properties. Omitted or true allows them.",
      +    "type": "boolean"
      +  },
      +  "properties": {
      +    "additionalProperties": {
      +      "additionalProperties": true,
      +      "properties": {
      +        "type": {
      +          "description": "Expected JSON type for this top-level field.",
      +          "enum": [
      +            "null",
      +            "array",
      +            "object",
      +            "string",
      +            "number",
      +            "boolean"
      +          ],
      +          "type": "string"
      +        }
      +      },
      +      "type": "object"
      +    },
      +    "description": "Top-level field definitions. Each field may declare a JSON type; other JSON Schema keywords are ignored.",
      +    "type": "object"
      +  },
      +  "required": {
      +    "description": "Top-level field names that must be present in value.",
      +    "items": {
      +      "type": "string"
      +    },
      +    "type": "array",
      +    "uniqueItems": true
      +  }
      +}
    • addedInput schema / properties / value / description
      Added value: +"JSON object to validate against the supported schema subset."
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
      +  "additionalProperties": false,
      +  "description": "MCP payment instruction. Calling the MCP tool itself does not charge or execute the paid operation.",
      +  "properties": {
      +    "endpoint": {
      +      "description": "ARN HTTP path to POST the same tool arguments to for paid execution.",
      +      "type": "string"
      +    },
      +    "instruction": {
      +      "description": "How to execute the capability after receiving the payment requirement.",
      +      "type": "string"
      +    },
      +    "paymentRequired": {
      +      "const": true,
      +      "description": "Always true for paid ARN capabilities exposed over MCP.",
      +      "type": "boolean"
      +    },
      +    "price": {
      +      "additionalProperties": false,
      +      "properties": {
      +        "amount": {
      +          "description": "Atomic asset amount.",
      +          "type": "string"
      +        },
      +        "asset": {
      +          "description": "Settlement asset.",
      +          "type": "string"
      +        },
      +        "display": {
      +          "description": "Human-readable current price.",
      +          "type": "string"
      +        },
      +        "network": {
      +          "description": "CAIP-2 settlement network identifier.",
      +          "type": "string"
      +        }
      +      },
      +      "required": [
      +        "amount",
      +        "asset",
      +        "network",
      +        "display"
      +      ],
      +      "type": "object"
      +    },
      +    "protocol": {
      +      "const": "x402",
      +      "description": "Payment protocol required by the HTTP execution endpoint.",
      +      "type": "string"
      +    }
      +  },
      +  "required": [
      +    "paymentRequired",
      +    "protocol",
      +    "endpoint",
      +    "price",
      +    "instruction"
      +  ],
      +  "type": "object"
      +}
  7. Changed2 schema fields changed
    • addedInput schema / properties
      Added value: +{
      +  "schema": {
      +    "type": "object"
      +  },
      +  "value": {
      +    "type": "object"
      +  }
      +}
    • addedInput schema / required
      Added value: +[
      +  "value",
      +  "schema"
      +]
  8. Added

TDQS

A4.3/5.0
Behavior5/5

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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds decisive context they cannot: this is a discovery call that does not execute the advertised capability, does not charge, and returns an x402 endpoint, price and payment guide. That reframes what calling the tool actually does and prevents a serious misread.

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?

Front-loaded with the capability, followed by supported-keyword scope, sibling routing, and the discovery/payment caveat. It is dense but every sentence carries information; the keyword enumeration is long yet functional.

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 an output schema present, the description needn't explain return values, and it still discloses the discovery/payment nature of the response. The supported-subset scope and the fail-closed behavior are covered, leaving little an agent needs before invoking.

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% and both parameters (value, schema) are well documented in the schema itself, so the baseline is 3. The description lists supported keywords but adds no syntax or format detail beyond what the schema already provides for these two params.

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 ('recursive JSON Schema checking for objects, arrays and scalars') and names the sibling it is not ('Prefer object_contract_check for a new simple top-level contract'). An agent can distinguish it from the many sibling validation tools without opening a schema.

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?

Names an explicit alternative (object_contract_check) and the condition that selects it (a new simple top-level contract), which is clear routing guidance. It stops short of stating when this tool is the right choice versus that sibling, so it is not fully two-sided.

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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