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NullClear Arbiter

by io.github.mithgalalfayez
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nullclear_escrow_x402_call

Execute an x402-gated HTTP API call through NullClear deferred schema escrow. Guarantees payment is only settled if upstream returns valid data matching your schema contract. Supports 10 free daily trial calls with zero wallet setup.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
methodNoGET
fallbacksNoOrdered fallback candidates for autonomous multi-seller failover routing (max 3)
targetUrlYesUpstream API endpoint demanding x402 payment
invariantsNoDeep value invariants (numeric bounds, regex, forbidden substrings, timestamp freshness)
jsonSchemaNoJSON Schema draft-07 contract that response must strictly satisfy
spendPolicyNoOutbound spend firewall limits (maxPerCallAtomic, maxDailyWalletAtomic)
minTrustScoreNoMinimum acceptable trust score for seller (0-100, default 50)
sellerAgentIdNoSeller's agent ID for reputation check and Sybil wash-trade gating
rejectRefusalsNoReject canonical LLM refusal strings (default: true)
requiredFieldsNoField paths that must exist in response

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed2 schema fields changed
    • addedInput schema / properties / invariants / items / properties
      Added value: +{
+  "eq": {},
+  "gt": {
+    "type": "number"
+  },
+  "gte": {
+    "type": "number"
+  },
+  "lt": {
+    "type": "number"
+  },
+  "lte": {
+    "type": "number"
+  },
+  "maxLength": {
+    "type": "number"
+  },
+  "maxStalenessSeconds": {
+    "type": "number"
+  },
+  "minLength": {
+    "type": "number"
+  },
+  "neq": {},
+  "notContains": {
+    "items": {
+      "type": "string"
+    },
+    "type": "array"
+  },
+  "path": {
+    "description": "Dot-notation property path",
+    "type": "string"
+  },
+  "pattern": {
+    "type": "string"
+  }
+}
    • addedInput schema / properties / invariants / items / required
      Added value: +[
+  "path"
+]
  2. First observed

TDQS

B3.4/5.0
Behavior4/5

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

Annotations already declare readOnly=false, idempotent=false, and openWorld=true, but the description adds genuinely new context: payment settles only if the upstream response satisfies the schema contract, and no wallet setup is needed for trial calls. It stops short of explaining refund/escrow-release behavior on failure or latency of settlement.

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?

Three tight sentences with the core value proposition (conditional settlement) front-loaded, followed by the trial-call incentive. No filler, though the trial-call sentence is more marketing than operational guidance.

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?

For a 10-parameter tool with deeply nested objects and no output schema, the description covers the escrow guarantee but says nothing about the return payload, failure modes, or how fallbacks/invariants/spendPolicy interact with settlement. It is adequate because the schema is richly documented, but not complete.

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 description coverage is 90%, so the schema itself documents targetUrl, invariants, fallbacks, spendPolicy, and the rest. The description only gestures at jsonSchema ('your schema contract') and does not clarify invariants, spend firewall limits, or fallback routing semantics, so it adds little beyond structured data.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb (Execute) and resource (x402-gated HTTP API call) plus the mechanism (NullClear deferred schema escrow), which is distinctive enough to separate it from generic fetch siblings. It never explicitly contrasts itself with nullclear_safe_fetch, so sibling differentiation is implied rather than stated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

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

There is no guidance on when to choose this over nullclear_safe_fetch or when not to use it, despite the sibling list containing an obvious alternative fetch tool. The '10 free daily trial calls' line hints at onboarding but is not usage guidance for selection.

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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