assay

Verify Post-Payment x402 Delivery & Mint SLA Receipt

assay_verify_delivery

Idempotent

Independently probe a paid x402/A2A provider after payment to verify delivery or confirm an SLA breach. Combines reported status_code with a live probe and binds tx_hash into an HMAC-SHA256 receipt. Returns {verdict ('delivery_verified'|'sla_breach_confirmed'), sla_breach, grade, score, sla_receipt ('asr_sla_...')}. Use only after paying a provider; before payment use assay_preflight. First 5 calls/IP free.

Input Schema

TableJSON Schema

Name	Required	Description
`target`	Yes	Public HTTPS URL of the remote MCP server, A2A agent, or x402 endpoint to inspect (e.g. 'https://tandem.ac/mcp'). Private and loopback IPs are blocked.
`tx_hash`	No	On-chain payment transaction hash (0x Base USDC hash or base58 Solana signature) to bind into the signed SLA receipt.
`status_code`	No	HTTP status code returned by the paid endpoint (e.g. '200', '502', '504'). Codes >= 500 trigger verdict='sla_breach_confirmed'.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`reason`	No
`dossier`	No
`receipt`	Yes
`verdict`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 17, 2026

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "dossier": {
+      "type": "object"
+    },
+    "reason": {
+      "type": "string"
+    },
+    "receipt": {
+      "type": "string"
+    },
+    "verdict": {
+      "type": "string"
+    }
+  },
+  "required": [
+    "verdict",
+    "receipt"
+  ],
+  "type": "object"
+}

Changed9 schema fields changedOct 17, 2026

changedInput schema / properties / status_code / description

Previous value: -"status_code for assay_verify_delivery"New value: +"HTTP status code returned by the paid endpoint (e.g. '200', '502', '504'). Codes >= 500 trigger verdict='sla_breach_confirmed'."

addedInput schema / properties / status_code / maxLength
```
Added value: +8
```
addedInput schema / properties / status_code / minLength
```
Added value: +0
```

changedInput schema / properties / target / description

Previous value: -"target for assay_verify_delivery"New value: +"Public HTTPS URL of the remote MCP server, A2A agent, or x402 endpoint to inspect (e.g. 'https://tandem.ac/mcp'). Private and loopback IPs are blocked."

addedInput schema / properties / target / maxLength
```
Added value: +512
```
addedInput schema / properties / target / minLength
```
Added value: +8
```

changedInput schema / properties / tx_hash / description

Previous value: -"tx_hash for assay_verify_delivery"New value: +"On-chain payment transaction hash (0x Base USDC hash or base58 Solana signature) to bind into the signed SLA receipt."

addedInput schema / properties / tx_hash / maxLength
```
Added value: +128
```
addedInput schema / properties / tx_hash / minLength
```
Added value: +0
```

First observedOct 16, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations only declare the safety profile (non-read-only, non-destructive, idempotent, open-world). The description adds real behavioral context beyond that: it performs a live probe combined with reported status_code and mints an HMAC-SHA256 receipt bound to tx_hash, i.e. it produces a persistent signed artifact and enforces a per-IP rate limit. Not stated: what happens if tx_hash is omitted or how errors/failed probes surface.

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 dense sentences, front-loaded with the action and followed by sequencing and return shape; little waste. Slight redundancy between the title and the opening clause about minting an SLA receipt.

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 3 params at full schema coverage, an output schema, and clear annotations, the description covers purpose, timing, rate limit, and verdict semantics. It repeats the return shape already covered by the output schema, but nothing an agent needs to invoke it correctly is missing.

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 3 baseline applies, but the description adds the causal rule that status_code >= 500 drives verdict='sla_breach_confirmed' and that tx_hash is bound into the receipt, clarifying how the parameters interact rather than restating them.

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?

Specific verb+resource+scope: 'Independently probe a paid x402/A2A provider after payment to verify delivery or confirm an SLA breach.' It names the sibling it replaces in the pre-payment phase (assay_preflight), so an agent can distinguish it from assay_probe and assay_get_ledger_policy without opening schemas.

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

Usage Guidelines5/5

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

Explicit sequencing rule: 'Use only after paying a provider; before payment use assay_preflight.' This gives both the when-to-use condition and the named alternative for the opposite condition, plus a free-tier constraint ('First 5 calls/IP free') that affects invocation strategy.

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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