Genesis402

Look up a receipt (free)

genesis402_receipt

Read-only

Fetch a receipt by id to confirm a paid call settled and delivered, showing task, amount, payment rail, transaction hash, settler, payer and timestamp. Read-only; nothing is charged.

Instructions

Free, no payment, read-only and idempotent. Fetches one receipt by id from the rail's public receipts feed (twin.unykorn.org/receipts) to confirm that a paid call was settled and delivered. Use after any paid call, or to check a genesis402_prove receipt, using the receipt id returned with that result. It does not list or search receipts; you need the exact id. Returns the receipt exactly as published: the task called, amount in USD, payment rail, settlement transaction hash, settler, payer and timestamp. An unknown id returns an error with HTTP status 404; nothing is charged either way.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`receipt_id`	Yes	The receipt id exactly as returned with a paid call result or by genesis402_prove, 4 to 80 characters.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`receipt`	Yes	The receipt exactly as published on the rail's receipts feed.
`receipt_id`	Yes	The id that was looked up.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.3.4Sep 29, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "additionalProperties": false,
+  "properties": {
+    "receipt": {
+      "additionalProperties": {},
+      "description": "The receipt exactly as published on the rail's receipts feed.",
+      "type": "object"
+    },
+    "receipt_id": {
+      "description": "The id that was looked up.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "receipt_id",
+    "receipt"
+  ],
+  "type": "object"
+}

Changed1 schema field changedv0.3.3Sep 29, 2026

changedInput schema / properties / receipt_id / description

Previous value: -"The receipt id returned with a paid call result."New value: +"The receipt id exactly as returned with a paid call result or by genesis402_prove, 4 to 80 characters."

Changed1 schema field changedv0.3.2Sep 26, 2026
- addedInput schema / properties / receipt_id / description
```
Added value: +"The receipt id returned with a paid call result."
```
First observedv0.3.1Sep 26, 2026

TDQS

A4.3/5.0

Behavior5/5

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

Goes well beyond the readOnlyHint/openWorldHint annotations: it declares the tool is free and charges nothing, is idempotent, that an unknown id produces an HTTP 404 error, and the external data source. That is exactly the kind of cost and failure-mode context an agent needs before calling.

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-loads the most decision-relevant fact (free, read-only, idempotent) and is otherwise tight. The sentence enumerating returned fields duplicates the output schema slightly and could be trimmed.

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?

Covers the id source, the error case, and the no-charge behavior, and an output schema already documents the return shape. Only minor redundancy in listing returned fields keeps it from being fully lean.

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 coverage is 100% and the schema description already explains that receipt_id comes from a paid call result or genesis402_prove with a 4-80 character range. The description restates that source but adds no new format or syntax detail, so baseline 3 applies.

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 (fetches) and resource (one receipt by id) and explicitly delimits scope: it does not list or search, and requires an exact id. An agent can separate this from listing-style siblings without opening any 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?

Gives clear triggers ('use after any paid call, or to check a genesis402_prove receipt') and a negative rule ('need the exact id'). It stops short of naming the sibling to use for listing/searching receipts, so it is not fully routable.

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