DropEngine x402 Agent Services

invoice_preflight_10_pages

Paid invoice OCR ($0.13 USDC on Base): process complete PDF/image invoices up to 10 pages. Oversized PDFs are rejected before OCR.

Agent entry points: risky external action → use Agent Action Gate when a combined action-specific safety assessment is needed; unclear capability/provider → use free /api/discover; constrained comparison between callable alternatives → use paid route_tool; known single capability → call the direct tool; multi-step objective → read the matching workflow recipe and call only relevant steps. Workflows are stateless recipes, not executors; calls are paid separately and are not bundle charged. Agent Action Gate does not approve payment, sign or broadcast transactions, evaluate seller reputation, replace transaction simulation, replace route_tool, or replace human approval.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`expected`	No
`mime_type`	No
`document_url`	No
`document_base64`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`meta`	No
`next`	No
`error`	No
`checks`	Yes
`result`	No
`status`	No
`invoice`	Yes
`payment`	No
`agent_ux`	No
`decision`	Yes
`evidence`	Yes
`warnings`	Yes
`source_sha256`	Yes
`pages_processed`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed7 schema fields changedOct 8, 2026

addedOutput schema / properties / agent_ux

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "error": {
+      "anyOf": [
+        {},
+        {
+          "type": "null"
+        }
+      ]
+    },
+    "meta": {
+      "additionalProperties": {},
+      "propertyNames": {
+        "type": "string"
+      },
+      "type": "object"
+    },
+    "next": {
+      "items": {},
+      "type": "array"
+    },
+    "payment": {
+      "additionalProperties": false,
+      "properties": {
+        "execution_status": {
+          "enum": [
+            "not_started",
+            "succeeded",
+            "failed",
+            "unknown"
+          ],
+          "type": "string"
+        },
+        "status": {
+          "enum": [
+            "not_required",
+            "required",
+            "settled",
+            "failed",
+            "unknown"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "status",
+        "execution_status"
+      ],
+      "type": "object"
+    },
+    "result": {},
+    "status": {
+      "enum": [
+        "succeeded",
+        "failed",
+        "partial",
+        "outcome_unknown"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "status",
+    "result",
+    "error",
+    "meta",
+    "payment",
+    "next"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / error

Added value: +{
+  "anyOf": [
+    {},
+    {
+      "type": "null"
+    }
+  ]
+}

addedOutput schema / properties / meta

Added value: +{
+  "additionalProperties": {},
+  "propertyNames": {
+    "type": "string"
+  },
+  "type": "object"
+}

addedOutput schema / properties / next

Added value: +{
+  "items": {},
+  "type": "array"
+}

addedOutput schema / properties / payment

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "execution_status": {
+      "enum": [
+        "not_started",
+        "succeeded",
+        "failed",
+        "unknown"
+      ],
+      "type": "string"
+    },
+    "status": {
+      "enum": [
+        "not_required",
+        "required",
+        "settled",
+        "failed",
+        "unknown"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "status",
+    "execution_status"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / result
```
Added value: +{}
```

addedOutput schema / properties / status

Added value: +{
+  "enum": [
+    "succeeded",
+    "failed",
+    "partial",
+    "outcome_unknown"
+  ],
+  "type": "string"
+}

First observedSep 28, 2026

TDQS

B3.4/5.0

Behavior3/5

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

With no annotations, the description carries the full burden, but it does disclose useful behavior: a paid operation at $0.13 USDC on Base and that oversized PDFs are rejected before OCR (implying no OCR work occurs on them). It stops short of covering payment/auth mechanics or whether rejected documents are charged, so it is partial rather than complete.

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

Conciseness3/5

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

The tool-specific portion is two tight, front-loaded sentences that lead with the action and price. However, the large 'Agent entry points' boilerplate block is generic, largely irrelevant to this single tool, and dilutes the definition.

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

Completeness3/5

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

An output schema exists, so return values need not be described, and pricing/format/limits are present. But for a 4-parameter paid OCR tool with a nested 'expected' verification object and clear sibling tiers, the absence of any parameter explanation and of explicit tier-selection guidance leaves real gaps.

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

Parameters2/5

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

Schema description coverage is 0%, so the description must compensate and it does not — none of document_url, document_base64, mime_type, or the nested 'expected' reconciliation object are explained. The 'expected' object in particular is non-obvious (it drives preflight verification against tax/total/subtotal/line_items) and is left entirely unexplained.

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 and resource ('process complete PDF/image invoices'), adds the exact scope limit ('up to 10 pages'), the input formats (PDF/image), and the pricing model. This clearly differentiates it from the tiered siblings invoice_preflight and invoice_preflight_50_pages without needing to open 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 Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description states the 10-page ceiling, which implicitly routes larger documents to invoice_preflight_50_pages, and the appended 'Agent entry points' block gives generic routing (direct tool for known capability, route_tool for comparison). However, that block is boilerplate shared across tools and never explicitly contrasts this tier against its sibling tiers or states when it should not be used.

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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