Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory
REMOTE · ASSAY.AGENTDIET.DEV
Live behavioral security verifier, schema auditor, and trust oracle for A2A, MCP & x402 agents.
Available components
Last scanned (6 hours ago)
Scores higher than 97% of remote servers
Reachable. Last reached 5 Nov 2026.
Category Security
How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. How we score → Why this is hard to score →
Endpoint Security91
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- Authorisation is enforced on tool calls, but the challenge carries no valid RFC 9728 metadata, so a client cannot discover where to get a token. See how to fix → View diagnostics → Fail
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- DNSSEC is configured correctly; the domain's records validate against the full chain to the root. View diagnostics → Pass
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability95
- 100% of prompts and resources have a non-trivial description (not blank, and not just the item's name).Pass
- AI-judged instruction clarity (excellent).Pass
- Tool/resource definitions use about 1454 tokens (~103/item across 14 items; 4 tools + 10 resources), lean.Pass
- Tools include usage examples.Pass
Stability & Change Management57
- Stability observed for 17 of 30 days with no destabilising changes; credit accrues until the full window elapses.Partial
Tool Coverage100
- 100% of tools have a non-trivial description (not blank, and not just the tool's name).Pass
- 100% of tool parameters carry a description.Pass
- Structured output schemas are declared (100% of tools); any adoption earns full credit.Pass
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 4 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 6 captured unit(s) of tool text and found none that tries to manipulate the model reading it.Pass
Capabilities100
- Implements a current MCP spec version (2026-07-28).Pass
- Supports UI / widget rendering.Pass
Every change we have recorded for this component, newest first. Security-relevant changes are always shown. ▲ marks a change for the better, ▼ a change for the worse; unmarked changes are neutral.
- 3 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 47 to 50. That category is still filling its 30-day observation window: 14 days of observed history at the previous scan, 15 at this one. The score rises as the window fills, whether or not the server changes.
- 1 Nov 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 40 to 43. That category is still filling its 30-day observation window: 12 days of observed history at the previous scan, 13 at this one. The score rises as the window fills, whether or not the server changes.
- 30 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 33 to 37. That category is still filling its 30-day observation window: 10 days of observed history at the previous scan, 11 at this one. The score rises as the window fills, whether or not the server changes.
- 28 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 27 to 30. That category is still filling its 30-day observation window: 8 days of observed history at the previous scan, 9 at this one. The score rises as the window fills, whether or not the server changes.
- 26 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 20 to 23. That category is still filling its 30-day observation window: 6 days of observed history at the previous scan, 7 at this one. The score rises as the window fills, whether or not the server changes.
- 24 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 13 to 17. That category is still filling its 30-day observation window: 4 days of observed history at the previous scan, 5 at this one. The score rises as the window fills, whether or not the server changes.
- 22 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 7 to 10. That category is still filling its 30-day observation window: 2 days of observed history at the previous scan, 3 at this one. The score rises as the window fills, whether or not the server changes.
- 21 Oct 26 +1
- DNSSEC: fail → pass ▲ security
Diagnostic detail from the automated scan of this channel: what the scanner observed at each step, so you can see exactly where a check passed or failed. It is informational only and never changes the trust score.
Captured 5 Nov 2026 · Probed https://assay.agentdiet.dev/mcp
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=agentdiet.dev | CN=YE2,O=Let's Encrypt,C=US | 19 Oct 2026 | 17 Jan 2027 | ECDSA 256 | ECDSA-SHA384 | 5298e9816f20b196c22328875c8dffe59d0 |
| SANs: *.agentdiet.dev, agentdiet.dev | ||||||
| CN=YE2,O=Let's Encrypt,C=US (CA) | CN=Root YE,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | ECDSA 384 | ECDSA-SHA384 | 4df3b15dd6c0784c507cd37b58e6f115 |
| CN=Root YE,O=ISRG,C=US (CA) | CN=ISRG Root X2,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | ECDSA-SHA384 | 872165fc34b6e5fba8add5b3705fb53a |
| CN=ISRG Root X2,O=Internet Security Research Group,C=US (CA) | CN=ISRG Root X1,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | ECDSA 384 | SHA256-RSA | 6c8f1dc727c7117f7baf853ac980f9cd |
Background: What to check on a remote MCP endpoint →
DNSSEC secure
Validation of assay.agentdiet.dev. — Secure
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| dev. | present | 60074 | 8 | Verified |
| agentdiet.dev. | present | 2371 | 13 | Verified |
| assay.agentdiet.dev. | Verified address RRset verified with the apex keys |
Authentication Challenged, unverified
The endpoint asked for a token, but we could not retrieve and validate the RFC 9728 metadata that tells a client how to obtain one.
| Result | Challenged, unverified |
|---|---|
| Enforced | On tool calls |
| HTTP status | 200 |
WWW-Authenticate challenge Bearer resource_metadata="https://assay-207908449630.us-central1.run.app/.well-known/oauth-protected-resource"
Bearer resource_metadata="https://assay-207908449630.us-central1.run.app/.well-known/oauth-protected-resource"| Header | Value |
|---|---|
| strict-transport-security | max-age=31536000; includeSubDomains |
Protected resource metadata
| Document | https://assay-207908449630.us-central1.run.app/.well-known/oauth-protected-resource |
|---|---|
| Retrieved | Yes |
| Problem | metadata_resource_mismatch |
| Resource | https://assay-207908449630.us-central1.run.app/mcp |
| Authorisation server | https://assay-207908449630.us-central1.run.app |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://assay.agentdiet.dev/mcp | Verified | 200 | |
| http (plaintext) | http://assay.agentdiet.dev/mcp | HTTPS enforced | 301 | https://assay.agentdiet.dev/mcp |
The tools this component advertises to a client, with an estimated token cost for each. Expand a tool to see its parameters and schema. The per-tool counts are indicative and are not scored directly; the schema's total context footprint is one signal in Schema Quality & AI Usability. A tool's description is untrusted text the model reads on every call, which is what makes this list a security surface and not just an inventory: how tool poisoning works →
assay_get_ledger_policy Query Historical Ledger & Pin Expected Schema Hashes ~271
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'.
| Name | Type | Req | Description |
|---|---|---|---|
| expected_tools_hash | string | – | Optional 64-char SHA-256 hex digest of the canonical MCP tools/list schema from mcp-lock.json. Omit to read or auto-pin the current live digest; pass a 64-hex digest to enforce zero-drift gating. |
| target | string | 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. |
| Name | Type | Req | Description |
|---|---|---|---|
| dossier | object | – | – |
| error | string|null | – | – |
| reason | string | – | – |
| receipt | string | yes | – |
| status | string | – | – |
| verdict | string | yes | – |
{"target":"https://agentdiet-72343955726.us-central1.run.app/mcp"}assay_preflight Pre-Flight MCP & A2A Security Gate ~281
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'.
| Name | Type | Req | Description |
|---|---|---|---|
| expected_tools_hash | string | – | Optional 64-char SHA-256 hex digest of the canonical MCP tools/list schema from mcp-lock.json. Omit to read or auto-pin the current live digest; pass a 64-hex digest to enforce zero-drift gating. |
| target | string | 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. |
| Name | Type | Req | Description |
|---|---|---|---|
| dossier | object | – | – |
| error | string|null | – | – |
| reason | string | – | – |
| receipt | string | yes | – |
| status | string | – | – |
| verdict | string | yes | – |
{"target":"https://agentdiet-72343955726.us-central1.run.app/mcp"}assay_probe Register & Refresh Endpoint Conformance Telemetry ~230
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'.
| Name | Type | Req | Description |
|---|---|---|---|
| target | string | 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. |
| Name | Type | Req | Description |
|---|---|---|---|
| dossier | object | – | – |
| error | string|null | – | – |
| reason | string | – | – |
| receipt | string | yes | – |
| status | string | – | – |
| verdict | string | yes | – |
{"target":"https://agentdiet-72343955726.us-central1.run.app/mcp"}assay_verify_delivery Verify Post-Payment x402 Delivery & Mint SLA Receipt ~313
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'.
| Name | Type | Req | Description |
|---|---|---|---|
| status_code | string | – | Optional HTTP status code returned by the paid endpoint (e.g. '200', '502', '504'). Codes >= 500 force verdict='sla_breach_confirmed' even if a retry probe succeeds. |
| target | string | 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 | string | – | Optional on-chain payment transaction hash (0x Base USDC hash or base58 Solana signature) to bind into the signed SLA receipt. Omit to run an unsigned post-call SLA check. |
| Name | Type | Req | Description |
|---|---|---|---|
| dossier | object | – | – |
| error | string|null | – | – |
| reason | string | – | – |
| receipt | string | yes | – |
| status | string | – | – |
| verdict | string | yes | – |
{"target":"https://agentdiet-72343955726.us-central1.run.app/mcp"}How do I install the Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory server?
Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory is a hosted endpoint at https://assay.agentdiet.dev/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.
remote · assay.agentdiet.dev
claude mcp add --transport http dev-agentdiet-assay 'https://assay.agentdiet.dev/mcp'
What is the Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory server?
Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory is listed in the public MCP registry as dev.agentdiet/assay. Live behavioral security verifier, schema auditor, and trust oracle for A2A, MCP & x402 agents. This page covers its hosted endpoint (https://assay.agentdiet.dev/mcp).
Is the Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory server safe to use?
Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory scores 89 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.
What tools does the Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory server expose?
Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory exposes 4 tools: assay_preflight, assay_probe, assay_verify_delivery, assay_get_ledger_policy. Their descriptions and schemas cost roughly 1,095 tokens of context every time the server is loaded.
Does the Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory server require authentication?
Yes. Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory asked us for credentials when we connected, so you will need to authorise it in your MCP client before it can do anything.
Is the Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory server still maintained?
Assay A2A, MCP & x402 Pre-Flight Verifier & Observatory is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.