Penny Press

essay_payment_info

Read-onlyIdempotent

Get the x402 payment details for one essay (price, network, asset, recipient wallet) so a machine buyer knows how to pay.

Input Schema

Name	Required	Description	Default
`slug`	Yes	Essay slug, e.g. river-of-time

Output Schema

Name	Required	Description
`slug`	Yes
`asset`	Yes	Payment asset, USDC
`price`	Yes	Price in USDC, e.g. $0.01
`title`	Yes
`network`	Yes	Chain id, e.g. eip155:8453 (Base mainnet)
`recipient`	Yes	Wallet receiving the payment
`machine_url`	Yes	Paid machine read via x402

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedSep 29, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": false,
+  "properties": {
+    "asset": {
+      "description": "Payment asset, USDC",
+      "type": "string"
+    },
+    "machine_url": {
+      "description": "Paid machine read via x402",
+      "type": "string"
+    },
+    "network": {
+      "description": "Chain id, e.g. eip155:8453 (Base mainnet)",
+      "type": "string"
+    },
+    "price": {
+      "description": "Price in USDC, e.g. $0.01",
+      "type": "string"
+    },
+    "recipient": {
+      "description": "Wallet receiving the payment",
+      "type": "string"
+    },
+    "slug": {
+      "type": "string"
+    },
+    "title": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "slug",
+    "title",
+    "price",
+    "asset",
+    "network",
+    "recipient",
+    "machine_url"
+  ],
+  "type": "object"
+}

First observedSep 28, 2026

TDQS

A4/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world behavior, so safety is covered. The description adds that the response is payment instructions aimed at a machine buyer, which is useful, but says nothing about auth requirements, staleness, or whether the values can change.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

One sentence, front-loaded with the verb and resource, with zero filler. Every clause earns its place.

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?

With an output schema present and annotations covering the safety profile, the description need not explain return values, and it already names the key fields. It is complete enough for an agent to call correctly; only peripheral behavior (auth, refresh semantics) is absent.

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 single slug parameter is documented with an example ("river-of-time"), so the schema carries the parameter semantics. The description only implies that slug selects one essay, adding nothing beyond the schema.

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 (Get) and resource (x402 payment details for one essay) and enumerates the returned fields (price, network, asset, recipient wallet). It is unmistakably distinct from the sibling list_essays.

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?

"so a machine buyer knows how to pay" gives clear context for when to reach for this tool (before initiating payment for a single essay). It does not name alternatives or exclusions, but the sibling list_essays is not a plausible substitute for per-essay payment info.

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

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