Decide whether an MCP server update breaks its callers
Decide whether an MCP server update breaks its callers. Classifies each change by direction: an agent produces the tool call and consumes its result, so an input-schema change breaks callers while an output-schema change breaks whatever reads the result. Also reports a tool that stopped declaring readOnlyHint, which is a consent change no schema diff would surface.
Not tested: has real-world effectsour last check, 2026-10-04
0 of 0checks answered this week
n/amedian answer time
$0.22listed price per call
n/aprice it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://api.zfinia.com/x402/v1/mcp-breaking-change-report
| Category | Everything else |
|---|---|
| Provider host | api.zfinia.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 1 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
We never call tools that send, buy, move money or file anything, not even without paying.
Example input (from the provider)
{
"body": {
"after": {
"capabilities": {
"tools": {
"listChanged": false
}
},
"serverInfo": {
"name": "orders-mcp",
"version": "2.0.0"
},
"tools": [
{
"annotations": {
"idempotentHint": true
},
"description": "List orders.",
"inputSchema": {
"properties": {
"page": {
"description": "Page number, starting at 1.",
"minimum": 1,
"type": "integer"
},
"region": {
"description": "Data region to query.",
"type": "string"
},
"status": {
"description": "Restrict to one status.",
"enum": [
"open",
"shipped",
"disputed"
],
"type": "string"
},
"tenant_id": {
"description": "The tenant whose orders to list.",
"type": "string"
}
},
"required": [
"tenant_id",
"region"
],
"type": "object"
},
"name": "list_orders",
"outputSchema": {
"properties": {
"items": {
"type": "array"
}
},
"required": [
"items"
],
"type": "object"
}
},
{
"annotations": {
"readOnlyHint": true
},
"description": "Fetch one order by its identifier, including line items and the current fulfilment state.",
"inputSchema": {
"properties": {
"order_id": {
"description": "The order identifier.",
"type": "string"
}
},
"required": [
"order_id"
],
"type": "object"
},
"name": "get_order"
},
{
"annotations": {
"destructiveHint": true,
"idempotentHint": false
},
"description": "Cancel an order that has not yet shipped. This cannot be undone and will issue a refund where one is due.",
"inputSchema": {
"properties": {
"order_id": {
"description": "The order to cancel.",
"type": "string"
},
"reason": {
"description": "Why it is being cancelled.",
"type": "string"
}
},
"required": [
"order_id"
],
"type": "object"
},
"name": "cancel_order"
}
]
},
"before": {
"capabilities": {
"resources": {
"subscribe": true
},
"tools": {
"listChanged": true
}
},
"serverInfo": {
"name": "orders-mcp",
"version": "1.3.0"
},
"tools": [
{
"annotations": {
"idempotentHint": true,
"readOnlyHint": true
},
"description": "List orders for a tenant, newest first, with optional paging. Returns only orders the caller is entitled to see.",
"inputSchema": {
"properties": {
"page": {
"description": "Page number, starting at 1.",
"minimum": 1,
"type": "integer"
},
"status": {
"description": "Restrict to one status.",
"enum": [
"open",
"shipped"
],
"type": "string"
},
"tenant_id": {
"description": "The tenant whose orders to list.",
"type": "string"
}
},
"required": [
"tenant_id"
],
"type": "object"
},
"name": "list_orders",
"outputSchema": {
"properties": {
"items": {
"type": "array"
},
"next_page": {
"type": [
"integer",
"null"
]
}
},
"required": [
"items"
],
"type": "object"
}
},
{
"annotations": {
"readOnlyHint": true
},
"description": "Fetch one order by its identifier, including line items and the current fulfilment state.",
"inputSchema": {
"properties": {
"order_id": {
"description": "The order identifier.",
"type": "string"
}
},
"required": [
"order_id"
],
"type": "object"
},
"name": "get_order",
"outputSchema": {
"properties": {
"id": {
"type": "string"
},
"total": {
"type": "number"
}
},
"required": [
"id"
],
"type": "object"
}
},
{
"annotations": {
"destructiveHint": true,
"idempotentHint": false
},
"description": "Cancel an order that has not yet shipped. This cannot be undone and will issue a refund where one is due.",
"inputSchema": {
"properties": {
"order_id": {
"description": "The order to cancel.",
"type": "string"
},
"reason": {
"description": "Why it is being cancelled.",
"type": "string"
}
},
"required": [
"order_id"
],
"type": "object"
},
"name": "cancel_order"
}
]
}
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"additionalProperties": false,
"properties": {
"after": {},
"before": {}
},
"required": [
"before",
"after"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}