DropEngine x402 Agent Services

verify_claim

Paid Freshness / Claim Verifier ($0.02 USDC). Checks a factual claim against fresh web search evidence and returns supported/contradicted/mixed/insufficient/stale with sources. Requires TAVILY_API_KEY. If the key is missing, returns a provider-unavailable error before requesting payment. Claim text is sent to the configured search provider.

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
`claim`	Yes
`freshness_days`	No
`preferred_domains`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`meta`	No
`next`	No
`claim`	Yes
`error`	No
`cached`	Yes
`result`	No
`status`	No
`payment`	No
`sources`	Yes
`success`	Yes
`verdict`	Yes
`agent_ux`	No
`degraded`	Yes
`evidence`	Yes
`warnings`	Yes
`freshness`	Yes
`confidence`	Yes
`verified_at`	Yes
`conflicting_evidence`	Yes

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"
+}

Changed1 schema field changedSep 29, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "additionalProperties": false,
+  "properties": {
+    "cached": {
+      "type": "boolean"
+    },
+    "claim": {
+      "type": "string"
+    },
+    "confidence": {
+      "type": "number"
+    },
+    "conflicting_evidence": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "published_at": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "snippet": {
+            "type": "string"
+          },
+          "source": {
+            "type": "string"
+          },
+          "source_quality": {
+            "type": "string"
+          },
+          "supports": {
+            "const": false,
+            "type": "boolean"
+          },
+          "title": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "source",
+          "title",
+          "published_at",
+          "source_quality",
+          "supports",
+          "snippet"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "degraded": {
+      "type": "boolean"
+    },
+    "evidence": {
+      "items": {
+        "additionalProperties": false,
+        "properties": {
+          "published_at": {
+            "type": [
+              "string",
+              "null"
+            ]
+          },
+          "snippet": {
+            "type": "string"
+          },
+          "source": {
+            "type": "string"
+          },
+          "source_quality": {
+            "type": "string"
+          },
+          "supports": {
+            "const": true,
+            "type": "boolean"
+          },
+          "title": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "source",
+          "title",
+          "published_at",
+          "source_quality",
+          "supports",
+          "snippet"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "freshness": {
+      "additionalProperties": false,
+      "properties": {
+        "age_days": {
+          "type": [
+            "number",
+            "null"
+          ]
+        },
+        "newest_source_at": {
+          "type": [
+            "string",
+            "null"
+          ]
+        },
+        "status": {
+          "enum": [
+            "fresh",
+            "stale",
+            "unknown"
+          ],
+          "type": "string"
+        }
+      },
+      "required": [
+        "status",
+        "newest_source_at",
+        "age_days"
+      ],
+      "type": "object"
+    },
+    "sources": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    },
+    "success": {
+      "const": true,
+      "type": "boolean"
+    },
+    "verdict": {
+      "enum": [
+        "supported",
+        "contradicted",
+        "mixed",
+        "insufficient_evidence",
+        "stale"
+      ],
+      "type": "string"
+    },
+    "verified_at": {
+      "type": "string"
+    },
+    "warnings": {
+      "items": {
+        "type": "string"
+      },
+      "type": "array"
+    }
+  },
+  "required": [
+    "success",
+    "claim",
+    "verdict",
+    "confidence",
+    "freshness",
+    "evidence",
+    "conflicting_evidence",
+    "warnings",
+    "sources",
+    "degraded",
+    "cached",
+    "verified_at"
+  ],
+  "type": "object"
+}

First observedSep 28, 2026

TDQS

A4.1/5.0

Behavior5/5

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

With no annotations, the description carries the full burden and does it well: it discloses the price ($0.02 USDC), the TAVILY_API_KEY requirement, the failure behavior (provider-unavailable error returned before payment is requested), and the privacy side effect (claim text is sent to the external search provider). These are exactly the non-obvious traits an agent must know before invoking.

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 core description is front-loaded and dense: price, function, output values, auth, and failure mode in four tight sentences. The appended routing paragraph is longer and server-wide boilerplate rather than tool-specific, so it dilutes rather than sharpens, but the essential content stays up front.

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?

An output schema exists, so return-structure explanation is optional (the verdict enumeration is a bonus), and the payment, key, error, and privacy behavior are covered. The main shortfall is the entirely undocumented parameters, which leaves an agent guessing at freshness and domain-filter semantics.

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% for all three parameters, so the description must compensate, and it largely does not. 'Fresh web search evidence' faintly hints at freshness_days, but the range/semantics of freshness_days and the purpose of preferred_domains (up to 10 domain filters) are never explained, and the claim length bounds (8-2000 chars) go unmentioned.

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 first sentence names a specific verb and resource (checks a factual claim) and enumerates the exact verdict space (supported/contradicted/mixed/insufficient/stale) plus the evidence returned (sources). This is clearly differentiable from siblings like check_url, scan_content, or extract_structured, which operate on URLs/content rather than claim truth.

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 entry-point routing block gives clear context: a known single capability means 'call the direct tool,' while comparisons go to route_tool and unclear capability to /api/discover. That is useful disambiguation, though the guidance is generic to the server rather than tailored to when claim verification specifically beats check_url or scan_content.

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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