assay

Record Live Endpoint Conformance Observation

assay_probe

Idempotent

Execute a live HTTP, A2A agent-card, and MCP tools/list probe against a target URL and record the observation in the Assay Observatory ledger without pre-flight policy gating. Returns the updated dossier {target, grade ('A+' to 'F'), score (0-100), mcp_tools, tools_hash, rug_pulls, poison_flags, latency_ms, receipt}. Use to index a server or refresh leaderboard telemetry; for allow/deny gating use assay_preflight. First 5 calls/IP free.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`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.

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"
+}

Changed3 schema fields changedOct 17, 2026

changedInput schema / properties / target / description

Previous value: -"target for assay_probe"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
```

First observedOct 16, 2026

TDQS

A4.3/5.0

Behavior4/5

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

Annotations cover the safety profile (readOnlyHint=false, openWorldHint=true, idempotentHint=true), and the description adds value beyond them: the probe is not policy-gated, it writes an observation to a ledger, it has a per-IP free-call quota ('First 5 calls/IP free'), and it returns latency/receipt metadata. It does not fully describe retry or quota-exceeded behavior, so it falls short of a 5.

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?

Two dense sentences, front-loaded with the action and record target, followed by routing guidance. The inline enumeration of return fields is partly redundant with the output schema, which costs a little tightness.

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?

With an output schema present, the description need not explain return values, and the scope, gating exclusion, and rate limit are covered. The meaning of 'without pre-flight policy gating' is left slightly implicit for an agent deciding between this and assay_preflight, but overall it is adequate for a one-parameter tool.

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 100% for the single 'target' parameter, including format, length bounds, and the private/loopback block, so the schema does the heavy lifting. The description adds no syntax or format detail beyond the schema; baseline 3 is appropriate.

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+resource: executes an HTTP/A2A/MCP probe against a target URL and records it in the Assay Observatory ledger. It also explicitly distinguishes itself from the sibling gating tool ('for allow/deny gating use assay_preflight'), so an agent can route correctly without opening the schema.

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?

Gives explicit when-to-use ('index a server or refresh leaderboard telemetry') and an explicit exclusion with a named alternative ('for allow/deny gating use assay_preflight'). The pre-flight-free behavior is also stated, clarifying it is not the policy-check path.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All assay tools Inspect

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