JSON Schema to MCP Tool Descriptor
Wrap a supported object-root JSON Schema in a deterministic MCP tool descriptor, optionally with an object-root output schema. Rejects unsupported keywords instead of silently weakening constraints. Does not deploy a tool, execute code, or claim provider-specific strict function compatibility.
api-assurance · Operation ID: json-schema-to-tool
Choose this operation when
- Create a named MCP tool descriptor from an object input schema
- Adapt a bounded JSON object schema into a tool definition
- Preserve schema constraints during tool registration preparation
Outside this profile
- OpenAI strict-mode conversion or arbitrary JSON Schema conversion
- Installing or running an MCP server
Exact release references
Static JSON contract · Markdown reference · Fixed example response
Complete input schema
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"name": {
"type": "string",
"minLength": 1,
"maxLength": 128,
"pattern": "^[A-Za-z0-9_.-]+$"
},
"description": {
"type": "string",
"minLength": 1,
"maxLength": 2048
},
"inputSchema": {
"$ref": "#/$defs/__schema0"
},
"outputSchema": {
"$ref": "#/$defs/__schema0"
}
},
"required": [
"name",
"description",
"inputSchema"
],
"additionalProperties": false,
"$defs": {
"__schema0": {
"anyOf": [
{
"type": "string"
},
{
"type": "number"
},
{
"type": "boolean"
},
{
"type": "null"
},
{
"type": "array",
"items": {
"$ref": "#/$defs/__schema0"
}
},
{
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {
"$ref": "#/$defs/__schema0"
}
}
]
}
}
}
Complete output-envelope schema
{
"type": "object",
"required": [
"operation",
"version",
"result",
"provenance"
],
"properties": {
"operation": {
"const": "json-schema-to-tool",
"type": "string"
},
"version": {
"const": "0.29.0",
"type": "string"
},
"result": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"properties": {
"profile": {
"type": "string",
"const": "typed-schema-subset-v1"
},
"descriptor": {
"type": "object",
"properties": {
"name": {
"type": "string"
},
"description": {
"type": "string"
},
"inputSchema": {
"$ref": "#/properties/result/$defs/__schema0"
},
"outputSchema": {
"$ref": "#/properties/result/$defs/__schema0"
}
},
"required": [
"name",
"description",
"inputSchema"
],
"additionalProperties": false
},
"warnings": {
"type": "array",
"items": {
"type": "string"
}
}
},
"required": [
"profile",
"descriptor",
"warnings"
],
"additionalProperties": false,
"$defs": {
"__schema0": {
"anyOf": [
{
"type": "string"
},
{
"type": "number"
},
{
"type": "boolean"
},
{
"type": "null"
},
{
"type": "array",
"items": {
"$ref": "#/properties/result/$defs/__schema0"
}
},
{
"type": "object",
"propertyNames": {
"type": "string"
},
"additionalProperties": {
"$ref": "#/properties/result/$defs/__schema0"
}
}
]
}
}
},
"provenance": {
"type": "object",
"required": [
"inputSha256",
"outputSha256",
"deterministic",
"externalRequests"
],
"properties": {
"inputSha256": {
"type": "string",
"pattern": "^[a-f0-9]{64}$"
},
"outputSha256": {
"type": "string",
"pattern": "^[a-f0-9]{64}$"
},
"deterministic": {
"const": true
},
"externalRequests": {
"const": 0
}
}
}
},
"additionalProperties": false
}
Fixed example
One accepted fixed example, not a custom-input trial. No operation runs when this static page is requested.
Example input
{
"name": "get_order",
"description": "Look up an order by its positive integer ID",
"inputSchema": {
"type": "object",
"properties": {
"id": {
"type": "integer",
"minimum": 1
}
},
"required": [
"id"
],
"additionalProperties": false
}
}
Example response
{
"operation": "json-schema-to-tool",
"version": "0.29.0",
"result": {
"profile": "typed-schema-subset-v1",
"descriptor": {
"name": "get_order",
"description": "Look up an order by its positive integer ID",
"inputSchema": {
"type": "object",
"properties": {
"id": {
"type": "integer",
"minimum": 1
}
},
"required": [
"id"
],
"additionalProperties": false
}
},
"warnings": [
"A descriptor is data, not an executable tool or a running MCP server",
"Tool descriptions are untrusted text; review before exposing to agents"
]
},
"provenance": {
"inputSha256": "278496984a5761d83ccfe31253b7c07535337ba0b112069638a70e90fea0da8c",
"outputSha256": "088217a6d0b8f139db4d12de1646e87f869a19e3d4eb8674c5b2be5d930d4a6e",
"deterministic": true,
"externalRequests": 0
}
}
Bounds and precision
JavaScript IEEE-754 numbers; use strings for large integer IDs/exact decimals where the schema accepts strings. No lossless numeric parsing.
{
"global": {
"requestBytes": 131072,
"responseBytes": 524288,
"jsonDepth": 32,
"jsonNodes": 20000,
"requestsPerMinute": 60,
"paidAttemptsPerMinute": 20,
"idempotencyHours": 24
},
"operation": {
"inputBytes": 110000,
"jsonNodes": 10000,
"depth": 24,
"schemaNodes": 128,
"schemaDepth": 12,
"schemaProperties": 64,
"findings": 200,
"outputBytes": 450000,
"jsonPointerCharacters": 4096
}
}
Complete schemas, descriptions and cross-field validation may impose additional limits.
Proposed price and protocol definitions
{
"unit": "one successful operation call",
"proposedNominalUsd": "0.01",
"sixDecimalTokenBaseUnits": "10000",
"subscription": false,
"includesPayerWalletOrNetworkFees": false,
"liveQuoteVerified": false,
"condition": "Actual SDK challenge is authoritative only within the caller's explicit authorization; configured six-decimal token peg is an operator assertion, not a conversion guarantee."
}
Protocol definitions: x402, mpp. MPP uses Tempo charge. Paid MCP execution is unsupported. All runtime readiness is not evaluated in this build.
API path templates, not endpoints on this documentation host
{
"x402": "/v1/x402/json-schema-to-tool",
"mpp": "/v1/mpp/json-schema-to-tool"
}
Required headers
{
"Content-Type": "application/json",
"Idempotency-Key": "random 16–128 character operation identifier"
}
Actual SDK challenge amount, asset, network, recipient and wallet costs must pass independent authorization. Preserve identical key, body, protocol and credential on retries; on PAYMENT_UNCERTAIN stop and reconcile.
Execution profile and provider conditions
{
"deterministic": true,
"externalRequests": 0,
"maxExternalRequests": 0,
"resultSnapshotPersisted": false,
"fixedExampleIsIllustrativeSnapshot": false,
"requiresPayment": true,
"supportsMcpExecution": false
}
Deterministic supplied-input operation with no external requests or stored request/result bodies. Payment infrastructure retains payment metadata and hashes.
Failure handling
- HTTP 400: Malformed JSON, missing/invalid idempotency key, or payment identifier mismatch Correct the request before payment
- HTTP 402: Payment challenge or rejected payment Use official protocol SDK; inspect payment outcome before another payment
- HTTP 409: Idempotency conflict, duplicate proof, or PAYMENT_UNCERTAIN Keep original key, body, and proof; reconcile uncertainty with operator; never blindly repay
- HTTP 413: Input or generated output too large Reduce input; no payment attempted for validation failure
- HTTP 415: Unsupported media type or compression Send uncompressed application/json
- HTTP 422: Schema or service-specific semantic validation failure Correct input using returned error code; no payment attempted
- HTTP 429: Request/payment-attempt rate exceeded Wait for rate limit window; preserve existing payment identity
- HTTP 503: Payment configuration/provider/state unavailable, or live DNS preparation failed before settlement Check readiness; DNS preparation failures may retry the identical key/body/credential only; uncertainty requires reconciliation
Declared requirements
Before any paid call, refresh the live operation contract and POST the complete bounded budgeted plan to the separate API's /preflight. Unknown requirements block selection; compatible preflight is not permission to spend.