mcp-gateway

ucp_cancel_checkout

DestructiveIdempotent

Cancel a UCP checkout session. Transitions to 'canceled' status. Cannot cancel already completed checkouts. PAYMENT MANDATE: this tool also requires one. Send it as the payment_mandate argument if your client cannot set headers, or as an X-Payment-Mandate header. It must carry mandate_id, max_amount_cents, currency, exp, sub, aud, and its currency must match the cart's currency or the call is denied outright. The cap in max_amount_cents is enforced against the cart total.

Input Schema

TableJSON Schema

Name	Required	Description
`reason`	No	Optional cancellation reason
`checkout_id`	Yes	UCP checkout session ID (valid UUID)
`idempotency_key`	No	Optional idempotency key to prevent duplicate cancellations.
`payment_mandate`	No	Payment mandate with `mandate_id`, `max_amount_cents`, `currency`, `exp`, `sub`, `aud`. Its `currency` must match the cart's. Use this when your client cannot set an `X-Payment-Mandate` header.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`id`	Yes
`label`	No
`intent`	No
`status`	Yes
`totals`	Yes
`currency`	Yes
`created_at`	Yes
`extensions`	No
`line_items`	Yes
`updated_at`	Yes
`idempotency_key`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 20, 2026

addedInput schema / properties / payment_mandate

Added value: +{
+  "anyOf": [
+    {
+      "additionalProperties": {},
+      "type": "object"
+    },
+    {
+      "type": "string"
+    }
+  ],
+  "description": "Payment mandate with `mandate_id`, `max_amount_cents`, `currency`, `exp`, `sub`, `aud`. Its `currency` must match the cart's. Use this when your client cannot set an `X-Payment-Mandate` header."
+}

Changed8 schema fields changedSep 17, 2026
- changedInput schema / additionalProperties
```
Previous value: -falseNew value: +true
```
- changedOutput schema / additionalProperties
```
Previous value: -falseNew value: +true
```
- changedOutput schema / properties / extensions / additionalProperties
```
Previous value: -falseNew value: +true
```
- changedOutput schema / properties / extensions / properties / warnings / items / additionalProperties
```
Previous value: -falseNew value: +true
```
- changedOutput schema / properties / intent / additionalProperties
```
Previous value: -falseNew value: +true
```
- changedOutput schema / properties / line_items / items / additionalProperties
```
Previous value: -falseNew value: +true
```
- changedOutput schema / properties / line_items / items / properties / price / additionalProperties
```
Previous value: -falseNew value: +true
```
- changedOutput schema / properties / totals / items / additionalProperties
```
Previous value: -falseNew value: +true
```
AddedSep 9, 2026
RemovedSep 1, 2026

Changed4 schema fields changedAug 24, 2026

addedInput schema / $schema

Added value: +"http://json-schema.org/draft-07/schema#"

addedInput schema / additionalProperties
```
Added value: +false
```

addedInput schema / properties

Added value: +{
+  "checkout_id": {
+    "description": "UCP checkout session ID (valid UUID)",
+    "type": "string"
+  },
+  "idempotency_key": {
+    "description": "Optional idempotency key to prevent duplicate cancellations.",
+    "type": "string"
+  },
+  "reason": {
+    "description": "Optional cancellation reason",
+    "type": "string"
+  }
+}

addedInput schema / required
```
Added value: +[
+  "checkout_id"
+]
```

Changed5 schema fields changedJul 10, 2026

removedInput schema / $schema

Removed value: -"http://json-schema.org/draft-07/schema#"

removedInput schema / additionalProperties
```
Removed value: -false
```

removedInput schema / properties

Removed value: -{
-  "checkout_id": {
-    "description": "UCP checkout session ID (valid UUID)",
-    "type": "string"
-  },
-  "idempotency_key": {
-    "description": "Optional idempotency key to prevent duplicate cancellations.",
-    "type": "string"
-  },
-  "reason": {
-    "description": "Optional cancellation reason",
-    "type": "string"
-  }
-}

removedInput schema / required
```
Removed value: -[
-  "checkout_id"
-]
```

changedOutput schema / (root)

Previous value: -{
-  "$schema": "http://json-schema.org/draft-07/schema#",
-  "additionalProperties": false,
-  "properties": {
-    "created_at": {
-      "type": "string"
-    },
-    "currency": {
-      "type": "string"
-    },
-    "extensions": {
-      "additionalProperties": false,
-      "properties": {
-        "warnings": {
-          "items": {
-            "additionalProperties": false,
-            "properties": {
-              "code": {
-                "type": "string"
-              },
-              "disclosure_url": {
-                "type": "string"
-              },
-              "message": {
-                "type": "string"
-              },
-              "severity": {
-                "enum": [
-                  "info",
-                  "caution",
-                  "critical"
-                ],
-                "type": "string"
-              }
-            },
-            "required": [
-              "code",
-              "message",
-              "severity"
-            ],
-            "type": "object"
-          },
-          "type": "array"
-        }
-      },
-      "type": "object"
-    },
-    "id": {
-      "type": "string"
-    },
-    "idempotency_key": {
-      "type": "string"
-    },
-    "intent": {
-      "additionalProperties": false,
-      "properties": {
-        "action": {
-          "type": "string"
-        },
-        "context": {
-          "type": "string"
-        },
-        "locale": {
-          "type": "string"
-        }
-      },
-      "required": [
-        "action"
-      ],
-      "type": "object"
-    },
-    "label": {
-      "type": "string"
-    },
-    "line_items": {
-      "items": {
-        "additionalProperties": false,
-        "properties": {
-          "id": {
-            "type": "string"
-          },
-          "price": {
-            "additionalProperties": false,
-            "properties": {
-              "amount": {
-                "type": "number"
-              },
-              "currency": {
-                "type": "string"
-              }
-            },
-            "required": [
-              "amount",
-              "currency"
-            ],
-            "type": "object"
-          },
-          "product_id": {
-            "type": "string"
-          },
-          "quantity": {
-            "type": "number"
-          },
-          "title": {
-            "type": "string"
-          }
-        },
-        "required": [
-          "id",
-          "product_id",
-          "title",
-          "quantity",
-          "price"
-        ],
-        "type": "object"
-      },
-      "type": "array"
-    },
-    "status": {
-      "enum": [
-        "incomplete",
-        "requires_escalation",
-        "ready_for_complete",
-        "complete_in_progress",
-        "completed",
-        "canceled"
-      ],
-      "type": "string"
-    },
-    "totals": {
-      "items": {
-        "additionalProperties": false,
-        "properties": {
-          "amount": {
-            "type": "number"
-          },
-          "currency": {
-            "type": "string"
-          },
-          "label": {
-            "type": "string"
-          }
-        },
-        "required": [
-          "label",
-          "amount",
-          "currency"
-        ],
-        "type": "object"
-      },
-      "type": "array"
-    },
-    "updated_at": {
-      "type": "string"
-    }
-  },
-  "required": [
-    "id",
-    "status",
-    "currency",
-    "line_items",
-    "totals",
-    "created_at",
-    "updated_at"
-  ],
-  "type": "object"
-}New value: +null

First observedApr 28, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations already mark the tool as destructive and idempotent, and the description adds substantial behavioral context beyond that: the payment mandate requirement, the header-vs-argument delivery option, the mandatory fields, the currency-match denial condition, and enforcement of max_amount_cents against the cart total. This is exactly the kind of non-obvious runtime behavior an agent needs.

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?

The description is front-loaded with the core action and then covers the mandatory payment mandate details. It is a bit dense, especially the uppercase PAYMENT MANDATE section, but every sentence serves a functional purpose given the hidden requirement and denial conditions.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given that an output schema exists and annotations cover safety, the description provides complete operational context: what happens on cancel, what is not cancellable, how the required payment mandate must be supplied, and what conditions cause denial. No critical calling information is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters5/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description adds critical semantics not fully visible in the schema: payment_mandate is actually required (though the schema lists it as optional) when not supplied as a header, its fields are enforced, its currency must match the cart, and the cap is enforced. This goes well beyond the schema's generic property descriptions.

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 states a specific verb and resource: 'Cancel a UCP checkout session.' It adds a concrete state transition ('Transitions to canceled status') and a distinguishing constraint ('Cannot cancel already completed checkouts'), which clearly separates this from sibling tools like complete_checkout or ucp_update_checkout.

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?

The description gives clear context for when to use the tool (cancel a UCP checkout) and an explicit exclusion (not already completed checkouts). It does not name alternatives such as complete_checkout for completed sessions, so it stops short of fully explicit when-not/alternative guidance.

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

All mcp-gateway tools Inspect

Try in Browser

One endpoint for every MCP toolRayrun runs every MCP server behind one URL and holds the credentials. Each call is decided per client, tool, and argument, then recorded.ray.runAd

Glama MCP Gateway

Add one secure layer between your agents and this server.

Resources

Need Help?