merona — x402 settlement index

trust_score

Read-onlyIdempotent

Score a specific seller wallet before paying it: wash-aware m.Score with an A–F grade, component breakdown, wash flags including multi-hop cycle detection, and the snapshot SHA so the result can be re-derived independently. Requires chain and address. Free — no key or payment needed. Optional: pass payment= to pay $0.001 via x402 and receive a settlement-receipted response.

Input Schema

TableJSON Schema

Name	Required	Description
`chain`	Yes	Chain the seller settles on, e.g. base, polygon, solana.
`address`	Yes	Seller wallet address to score.
`api_key`	No	merona API key. Alternative to per-call x402 payment.
`payment`	No	Base64 X-PAYMENT payload for a single x402 payment.

Output Schema

TableJSON Schema

Name	Required	Description
`tier`	No	unrated \| provisional \| verified.
`error`	No	Present only on failure.
`grade`	No	A–F letter; null means unrated (evidence gate, not an adverse signal).
`score`	No	Numeric m.Score behind the letter.
`delivery`	No	Paid-probe delivery evidence, when merona has bought from this seller: status delivery_verified (dated) or charged_unserved (payment settled, request refused; settlement tx included). This score covers base/polygon/solana, but delivery evidence is base-only today (see PROBE_COVERAGE_CHAINS) — null here on polygon/solana means no probe was possible, not a clean record.
`components`	No	Score component breakdown.
`snapshot_sha256`	No	Snapshot hash for independent re-derivation.
`payment_required`	No	x402 payment instructions; present only when the call is unpaid.
`suggested_action`	No	Deterministic action hint (PROCEED/CAUTION/INVESTIGATE/DECLINE/INSUFFICIENT_EVIDENCE) with reasons and rule version.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedAug 17, 2026

changedOutput schema / properties / delivery / description

Previous value: -"Paid-probe delivery evidence, when merona has bought from this seller: status delivery_verified (dated) or charged_unserved (payment settled, request refused; settlement tx included)."New value: +"Paid-probe delivery evidence, when merona has bought from this seller: status delivery_verified (dated) or charged_unserved (payment settled, request refused; settlement tx included). This score covers base/polygon/solana, but delivery evidence is base-only today (see PROBE_COVERAGE_CHAINS) — null here on polygon/solana means no probe was possible, not a clean record."

Changed1 schema field changedAug 7, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "additionalProperties": true,
+  "description": "The seller's score, or x402 payment instructions when called without api_key/payment.",
+  "properties": {
+    "components": {
+      "description": "Score component breakdown.",
+      "type": "object"
+    },
+    "delivery": {
+      "description": "Paid-probe delivery evidence, when merona has bought from this seller: status delivery_verified (dated) or charged_unserved (payment settled, request refused; settlement tx included).",
+      "type": "object"
+    },
+    "error": {
+      "description": "Present only on failure.",
+      "type": "string"
+    },
+    "grade": {
+      "description": "A–F letter; null means unrated (evidence gate, not an adverse signal).",
+      "type": [
+        "string",
+        "null"
+      ]
+    },
+    "payment_required": {
+      "description": "x402 payment instructions; present only when the call is unpaid.",
+      "type": "object"
+    },
+    "score": {
+      "description": "Numeric m.Score behind the letter.",
+      "type": [
+        "number",
+        "null"
+      ]
+    },
+    "snapshot_sha256": {
+      "description": "Snapshot hash for independent re-derivation.",
+      "type": "string"
+    },
+    "suggested_action": {
+      "description": "Deterministic action hint (PROCEED/CAUTION/INVESTIGATE/DECLINE/INSUFFICIENT_EVIDENCE) with reasons and rule version.",
+      "type": "object"
+    },
+    "tier": {
+      "description": "unrated | provisional | verified.",
+      "type": "string"
+    }
+  },
+  "type": "object"
+}

Changed4 schema fields changedAug 6, 2026

addedInput schema / properties / address / description
```
Added value: +"Seller wallet address to score."
```

addedInput schema / properties / api_key / description

Added value: +"merona API key. Alternative to per-call x402 payment."

addedInput schema / properties / chain / description

Added value: +"Chain the seller settles on, e.g. base, polygon, solana."

addedInput schema / properties / payment / description

Added value: +"Base64 X-PAYMENT payload for a single x402 payment."

First observedAug 6, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds meaningful behavioral details: the score is wash-aware, includes multi-hop cycle detection, provides a snapshot SHA for independent re-derivation, and explains the free vs. paid settlement-receipted response path. No contradiction with annotations.

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?

The description is two sentences, front-loaded with the primary purpose. Every clause adds useful information—the output features, the free nature, and the optional payment—with no redundancy or filler.

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?

Given the tool's moderate complexity, the description covers the core use case, free vs. optional payment behavior, and key output characteristics. An explicit alternative to sibling tools and potential edge cases would improve completeness, but the presence of rich annotations and an output schema means the description doesn't need to over-explain.

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

Parameters4/5

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 goes beyond the schema by explicitly stating that chain and address are required, and by giving a concrete usage example for the optional payment parameter ('pass payment=<base64 X-PAYMENT payload>'). This adds value over the raw 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?

The description opens with a specific verb+resource: 'Score a specific seller wallet before paying it'. It details the output (wash-aware m.Score, A–F grade, component breakdown, wash flags, snapshot SHA), distinguishing it from sibling tools that handle stats, mismatch feeds, or payment checks.

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 provides clear usage context: score before paying a seller, and it's free with no key or payment needed. It also explains the optional x402 payment path. However, it does not explicitly contrast with sibling tools or give when-not-to-use scenarios, so it falls short of a 5.

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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