Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory MCP Server

by agentdiet Your server? Claim it

answering

Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory is answering right now. Last checked 12 min ago. It exposes 4 tools. Last commit 17 Oct 2026.

Live behavioral security verifier, schema auditor, and trust oracle for A2A, MCP & x402 agents.

Uptime history 7 days of history

7 days agonow

100.0%

Uptime 24h

91 of 91 checks

Tools

read from the server

365 ms

Response time

average over 24h

Stars

last commit 17 Oct 2026

Nothing serious here today

Today is the operative word: we check Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 12 min ago.

Claude Code Claude Desktop Codex Cursor VS Code

run in your terminal

claude mcp add assay --transport http https://assay.agentdiet.dev/mcp

Settings → Connectors → Add custom connector, then paste this address

https://assay.agentdiet.dev/mcp

~/.codex/config.toml

[mcp_servers.assay]
url = "https://assay.agentdiet.dev/mcp"

.cursor/mcp.json

{
  "mcpServers": {
    "assay": {
      "url": "https://assay.agentdiet.dev/mcp"
    }
  }
}

.vscode/mcp.json

{
  "servers": {
    "assay": {
      "type": "http",
      "url": "https://assay.agentdiet.dev/mcp"
    }
  }
}

Available tools 4

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

assay

assay_get_ledger_policy

Retrieve historical conformance observations and manage pinned SHA-256 tools/list policy hashes in the Assay ledger for a target endpoint. When expected_tools_hash is provided, it pins that 64-hex digest as the target's baseline policy and compares it against the latest stored observation; when omitted, it returns the stored dossier and last 20 drift observations without network probing unless the target is unindexed. Idempotent; first 5 calls/IP are free. Use to audit historical drift or pin mcp-lock.json hashes; for live pre-execution gating use assay_preflight; for live re-indexing use assay_probe; for post-payment SLA receipts use assay_verify_delivery. Example: target='https://agentdiet-72343955726.us-central1.run.app/mcp'.

assay_preflight

Gate a remote MCP, A2A, or x402 endpoint before calling or paying it by probing live JSON-RPC reachability, hashing tools/list (SHA-256), and scanning for prompt-injection poisoning. When expected_tools_hash is provided, any mismatch against the live tools/list digest forces verdict='deny' to block silent schema rug-pulls; when omitted, verdict reflects liveness and injection safety alone. Read-only gate; first 5 calls/IP are free and quota-exceeded calls return a 402 top-up prompt. Use before tool execution or payment; to register or refresh public leaderboard telemetry use assay_probe; to read or pin stored policy hashes use assay_get_ledger_policy; after payment use assay_verify_delivery. Example: target='https://agentdiet-72343955726.us-central1.run.app/mcp'.

assay_probe

Register a new remote MCP, A2A, or x402 endpoint or refresh its public Assay Observatory dossier by running a live HTTP, agent-card, and JSON-RPC tools/list inspection without policy gating. Target must be a public HTTPS origin (private IPs are rejected with a 400 error); each call appends a timestamped observation and increments rug_pulls if tools_hash drifted since the prior stored observation. Writes to the public ledger; first 5 calls/IP are free and retries are idempotent on steady schemas. Use to onboard or re-index a server; for pre-call allow/deny gating use assay_preflight; for historical observations or hash pinning use assay_get_ledger_policy; for post-payment disputes use assay_verify_delivery. Example: target='https://agentdiet-72343955726.us-central1.run.app/mcp'.

assay_verify_delivery

Audit a paid x402 or A2A provider after payment to confirm delivery or prove an SLA breach with an HMAC-SHA256 signed receipt. Passing status_code >= 500 forces verdict='sla_breach_confirmed' even if the live re-probe succeeds, while passing tx_hash cryptographically binds your Base or Solana payment signature into the receipt (omitting tx_hash still verifies liveness and issues a probe-bound receipt). Non-destructive; first 5 calls/IP are free and failed target connections do not throw tool errors. Use only after paying a provider; before payment use assay_preflight; for public indexing use assay_probe; for policy history use assay_get_ledger_policy. Example: target='https://agentdiet-72343955726.us-central1.run.app/mcp'.

Endpoints

URL	Transport	State	Latency	Checked
https://assay.agentdiet.dev/mcp	streamable-http	answering	304 ms	12 min ago

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Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory — questions

Answers built from our own checks of this server.

What can Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory do?

It exposes 4 tools, read directly from the server on our last check. Among them: assay_get_ledger_policy, assay_preflight, assay_probe, assay_verify_delivery. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →

Is Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory working right now?

We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 365 ms. The bar chart above shows every period we have measured.

How do I connect Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory?

Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.

Does Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory need an API key?

No. Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 4 of them are readable on this page. This is what we observed, not what the docs claim.

How fast is Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory?

It answers our handshake in 365 ms on average, which is faster than 41% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.

Is Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory open source?

The code is open source: it is published under the MIT licence, written in Python, 0 stars on GitHub and 1 open issue. The licence covers the code in the repository, not the hosted service at assay.agentdiet.dev, which runs on its operator's own terms.