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OpenAPI Specification
openapi: 3.2.0
info:
title: DefaultBench MCP API
version: 1.0.0
summary: Machine-first paid placement and discovery for autonomous agents.
description: DefaultBench exposes transparent sponsored rankings. Listings are ordered by cumulative verified USDC payment descending, then by the time the current cumulative total was reached ascending. Rank is paid placement, not an endorsement or quality signal. Monetary values are decimal strings containing integer USDC base units (six decimals).
termsOfService: https://defaultbench.com/terms
license:
name: Proprietary service API; public protocol documentation
url: https://defaultbench.com/terms
servers:
- url: https://defaultbench.com
description: Configured DefaultBench origin
tags:
- name: MCP
description: MCP Streamable HTTP transport.
paths:
/mcp:
description: MCP Streamable HTTP transport. Every request consumes the configured search-rate ceiling in a separate MCP scope; POST bodies are capped at 64 KiB.
get:
operationId: openMcpStream
tags:
- MCP
summary: Open or resume an MCP Streamable HTTP event stream
parameters:
- $ref: '#/components/parameters/McpProtocolVersion'
- $ref: '#/components/parameters/McpSessionId'
responses:
'200':
description: MCP Streamable HTTP response when GET is negotiated by the transport.
content:
application/json:
schema:
$ref: '#/components/schemas/JsonRpcMessage'
text/event-stream:
schema:
type: string
'403':
description: A browser Origin header does not equal configured APP_ORIGIN.
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- error
properties:
error:
type: string
const: invalid_origin
'405':
description: GET is not available for the stateless transport state.
'421':
description: The request URL authority does not equal configured APP_ORIGIN.
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- error
properties:
error:
type: string
const: invalid_host
'429':
description: The applicable bounded rate limit is exhausted.
headers:
Retry-After:
$ref: '#/components/headers/RetryAfter'
RateLimit-Limit:
$ref: '#/components/headers/RateLimitLimit'
RateLimit-Remaining:
$ref: '#/components/headers/RateLimitRemaining'
RateLimit-Reset:
$ref: '#/components/headers/RateLimitReset'
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: rate_limit_exceeded
message: Rate limit exceeded. Retry after the indicated delay.
details: {}
retry_after_seconds: 30
'500':
description: An unexpected server error occurred; no uncertain payment is credited.
headers:
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: internal_error
message: The request could not be completed.
details: {}
'503':
description: A dependency is unavailable, one identical request owns the settlement claim, settlement is uncertain, or a confirmed settlement is awaiting atomic ranking credit. These responses never authorize a replacement payment. Retry the identical paid request after Retry-After unless the code says otherwise.
headers:
Retry-After:
$ref: '#/components/headers/RetryAfter'
PAYMENT-RESPONSE:
$ref: '#/components/headers/PaymentResponse'
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
examples:
dependencyUnavailable:
value:
error:
code: service_unavailable
message: A required dependency is temporarily unavailable.
details:
retryable: true
settlementInProgress:
value:
error:
code: payment_settlement_in_progress
message: An identical settlement attempt is already in progress. Retry this request shortly.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
settlement_state: settling
transaction_id: null
retryable: true
settlementUncertain:
value:
error:
code: payment_settlement_uncertain
message: The settlement outcome is being reconciled and will not be submitted again automatically. Retry this identical request for the durable result.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
settlement_state: settlement_uncertain
transaction_id: null
retryable: true
settledPendingCredit:
value:
error:
code: payment_settled_pending_credit
message: Settlement succeeded, but ranking credit is pending durable recovery. Retry the identical request.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
transaction_id: '0x0000000000000000000000000000000000000000000000000000000000000001'
retryable: true
bidConfigurationUnavailable:
value:
error:
code: bid_configuration_unavailable
message: Bidding is temporarily unavailable while payment policy configuration is synchronized.
details:
retryable: true
post:
operationId: sendMcpMessage
tags:
- MCP
summary: Send an MCP 2026-07-28 JSON-RPC message
parameters:
- $ref: '#/components/parameters/McpProtocolVersion'
- $ref: '#/components/parameters/McpSessionId'
requestBody:
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/JsonRpcMessage'
responses:
'200':
description: MCP JSON-RPC response or event stream.
content:
application/json:
schema:
$ref: '#/components/schemas/JsonRpcMessage'
text/event-stream:
schema:
type: string
'202':
description: Accepted notification or response with no response body.
'400':
description: The request is malformed or a query parameter is invalid.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
examples:
invalidKeyword:
value:
error:
code: invalid_keyword
message: Keyword must normalize to 1–64 valid characters.
details: {}
validationError:
value:
error:
code: validation_error
message: Request validation failed.
details:
fields:
- path: limit
message: 'Too big: expected number to be <=100'
'403':
description: A browser Origin header does not equal configured APP_ORIGIN.
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- error
properties:
error:
type: string
const: invalid_origin
'413':
description: The request body exceeds the 64 KiB limit.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: payload_too_large
message: Request body exceeds 64 KiB.
details: {}
'421':
description: The request URL authority does not equal configured APP_ORIGIN.
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- error
properties:
error:
type: string
const: invalid_host
'429':
description: The applicable bounded rate limit is exhausted.
headers:
Retry-After:
$ref: '#/components/headers/RetryAfter'
RateLimit-Limit:
$ref: '#/components/headers/RateLimitLimit'
RateLimit-Remaining:
$ref: '#/components/headers/RateLimitRemaining'
RateLimit-Reset:
$ref: '#/components/headers/RateLimitReset'
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: rate_limit_exceeded
message: Rate limit exceeded. Retry after the indicated delay.
details: {}
retry_after_seconds: 30
'500':
description: An unexpected server error occurred; no uncertain payment is credited.
headers:
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: internal_error
message: The request could not be completed.
details: {}
'503':
description: A dependency is unavailable, one identical request owns the settlement claim, settlement is uncertain, or a confirmed settlement is awaiting atomic ranking credit. These responses never authorize a replacement payment. Retry the identical paid request after Retry-After unless the code says otherwise.
headers:
Retry-After:
$ref: '#/components/headers/RetryAfter'
PAYMENT-RESPONSE:
$ref: '#/components/headers/PaymentResponse'
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
examples:
dependencyUnavailable:
value:
error:
code: service_unavailable
message: A required dependency is temporarily unavailable.
details:
retryable: true
settlementInProgress:
value:
error:
code: payment_settlement_in_progress
message: An identical settlement attempt is already in progress. Retry this request shortly.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
settlement_state: settling
transaction_id: null
retryable: true
settlementUncertain:
value:
error:
code: payment_settlement_uncertain
message: The settlement outcome is being reconciled and will not be submitted again automatically. Retry this identical request for the durable result.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
settlement_state: settlement_uncertain
transaction_id: null
retryable: true
settledPendingCredit:
value:
error:
code: payment_settled_pending_credit
message: Settlement succeeded, but ranking credit is pending durable recovery. Retry the identical request.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
transaction_id: '0x0000000000000000000000000000000000000000000000000000000000000001'
retryable: true
bidConfigurationUnavailable:
value:
error:
code: bid_configuration_unavailable
message: Bidding is temporarily unavailable while payment policy configuration is synchronized.
details:
retryable: true
delete:
operationId: closeMcpSession
tags:
- MCP
summary: Close an MCP Streamable HTTP session when supported
parameters:
- $ref: '#/components/parameters/McpProtocolVersion'
- $ref: '#/components/parameters/McpSessionId'
responses:
'200':
description: MCP transport accepted the session close.
'403':
description: A browser Origin header does not equal configured APP_ORIGIN.
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- error
properties:
error:
type: string
const: invalid_origin
'404':
description: The requested resource does not exist.
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: not_found
message: The requested resource was not found.
details: {}
'405':
description: The stateless transport has no session to close.
'421':
description: The request URL authority does not equal configured APP_ORIGIN.
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- error
properties:
error:
type: string
const: invalid_host
'429':
description: The applicable bounded rate limit is exhausted.
headers:
Retry-After:
$ref: '#/components/headers/RetryAfter'
RateLimit-Limit:
$ref: '#/components/headers/RateLimitLimit'
RateLimit-Remaining:
$ref: '#/components/headers/RateLimitRemaining'
RateLimit-Reset:
$ref: '#/components/headers/RateLimitReset'
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: rate_limit_exceeded
message: Rate limit exceeded. Retry after the indicated delay.
details: {}
retry_after_seconds: 30
'500':
description: An unexpected server error occurred; no uncertain payment is credited.
headers:
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
example:
error:
code: internal_error
message: The request could not be completed.
details: {}
'503':
description: A dependency is unavailable, one identical request owns the settlement claim, settlement is uncertain, or a confirmed settlement is awaiting atomic ranking credit. These responses never authorize a replacement payment. Retry the identical paid request after Retry-After unless the code says otherwise.
headers:
Retry-After:
$ref: '#/components/headers/RetryAfter'
PAYMENT-RESPONSE:
$ref: '#/components/headers/PaymentResponse'
X-Request-Id:
$ref: '#/components/headers/RequestId'
content:
application/json:
schema:
$ref: '#/components/schemas/ErrorResponse'
examples:
dependencyUnavailable:
value:
error:
code: service_unavailable
message: A required dependency is temporarily unavailable.
details:
retryable: true
settlementInProgress:
value:
error:
code: payment_settlement_in_progress
message: An identical settlement attempt is already in progress. Retry this request shortly.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
settlement_state: settling
transaction_id: null
retryable: true
settlementUncertain:
value:
error:
code: payment_settlement_uncertain
message: The settlement outcome is being reconciled and will not be submitted again automatically. Retry this identical request for the durable result.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
settlement_state: settlement_uncertain
transaction_id: null
retryable: true
settledPendingCredit:
value:
error:
code: payment_settled_pending_credit
message: Settlement succeeded, but ranking credit is pending durable recovery. Retry the identical request.
details:
idempotency_key: bid_01JQ4Z6W2YW1FVD5QAPGMF6M4Q
transaction_id: '0x0000000000000000000000000000000000000000000000000000000000000001'
retryable: true
bidConfigurationUnavailable:
value:
error:
code: bid_configuration_unavailable
message: Bidding is temporarily unavailable while payment policy configuration is synchronized.
details:
retryable: true
components:
parameters:
McpSessionId:
name: Mcp-Session-Id
in: header
required: false
schema:
type: string
minLength: 1
maxLength: 256
McpProtocolVersion:
name: MCP-Protocol-Version
in: header
required: true
schema:
type: string
const: '2026-07-28'
schemas:
ErrorResponse:
type: object
additionalProperties: false
required:
- error
properties:
error:
type: object
additionalProperties: false
required:
- code
- message
- details
properties:
code:
type: string
pattern: ^[a-z][a-z0-9_]*$
description: Stable machine-readable code.
message:
type: string
description: Human-readable, non-stable explanation.
details:
$ref: '#/components/schemas/ErrorDetail'
retry_after_seconds:
type: integer
minimum: 1
JsonRpcMessage:
type: object
additionalProperties: true
required:
- jsonrpc
properties:
jsonrpc:
type: string
const: '2.0'
id:
oneOf:
- type: string
- type: integer
- type: 'null'
method:
type: string
params:
type: object
additionalProperties: true
result: {}
error:
type: object
additionalProperties: true
ErrorDetail:
type: object
description: Code-specific bounded details; clients must branch on error.code, not message text.
additionalProperties: true
headers:
RetryAfter:
description: Seconds until the caller should retry.
schema:
type: integer
minimum: 1
RateLimitLimit:
description: Maximum requests in the current policy window.
schema:
type: integer
minimum: 1
RateLimitRemaining:
description: Requests remaining in the current policy window.
schema:
type: integer
minimum: 0
PaymentResponse:
description: Base64-encoded JSON x402 v2 settlement response/receipt. It may also be present on a non-200 facilitator failure or uncertain response; header presence alone is never evidence of success or ranking credit.
schema:
type: string
contentEncoding: base64
RequestId:
description: Opaque request correlation identifier; safe to include in an incident report.
schema:
type: string
RateLimitReset:
description: Unix epoch timestamp in seconds when the current policy window resets.
schema:
type: integer
minimum: 0
securitySchemes:
x402Payment:
type: apiKey
in: header
name: PAYMENT-SIGNATURE
description: Base64-encoded x402 v2 payment payload. It is intentionally absent on the initial request that obtains HTTP 402 requirements.
sellerAnalyticsBearer:
type: http
scheme: bearer
bearerFormat: DefaultBench signed token
description: Five-minute token issued only after consuming a listing-bound, origin-bound EIP-712 wallet challenge.
operatorBearer:
type: http
scheme: bearer
description: Operator secret for private revenue and purchase-funnel metrics.
externalDocs:
description: Full autonomous-client instructions
url: https://defaultbench.com/llms-full.txt
x-defaultbench-payment:
protocol: x402
version: 2
sdkVersion: 2.24.0
scheme: exact
network: eip155:8453
networkLabel: Base mainnet
asset: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913'
symbol: USDC
decimals: 6
minimumBidBaseUnits: '10000'
requestHeader: PAYMENT-SIGNATURE
challengeHeader: PAYMENT-REQUIRED
settlementHeader: PAYMENT-RESPONSE
x-defaultbench-ranking:
primary: cumulative verified payment descending
tieBreaker: timestamp current cumulative total was reached ascending
qualitySignal: false
x-defaultbench-examples: Synthetic documentation examples; never production activity.