Voice Agent Linter
REMOTE · MCP.MODERNMUSTARDSEED.COM
Lints a phone voice agent prompt and platform config before real callers reach it.
Available components
Last scanned (15 hours ago)
Scores higher than 66% of remote servers
Reachable. Last reached 17 Oct 2026.
Category Testing and QA
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 Security80
- The endpoint's TLS certificate is valid, in date, and uses a strong key. View diagnostics → Pass
- No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one. See how to fix → View diagnostics → Partial
- HTTPS is enforced; there's no plaintext access path. View diagnostics → Pass
- The HSTS (Strict-Transport-Security) header is present. View diagnostics → Pass
- DNSSEC check failed: this domain isn't protected by DNSSEC. See how to fix → View diagnostics → Fail
Transport & Reachability100
- Verified streamable-http transport via a live MCP handshake. View diagnostics → Pass
Schema Quality & AI Usability64
- AI-judged instruction clarity (excellent).Pass
- Context-footprint check failed: tool/resource definitions use about 777 tokens (~259/item across 3 items; 3 tools + 0 resources), over budget; trim descriptions and params. See how to fix → Fail
- Usage-examples check failed: none of the tools include examples. See how to fix → Fail
Stability & Change Management17
- Stability observed for 5 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
Tool Safety100
- No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.Pass
- We read all 3 captured tool definition(s), and no name or description among them implies an irreversible operation.Pass
- An AI judge read all 4 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
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.
- 17 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.
- 14 Oct 26 +1
No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.
- 13 Oct 26 0
- Stability: unverified → 0.03 ▲ functional
- 12 Oct 26 72
First indexed and scored.
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 17 Oct 2026 · Probed https://mcp.modernmustardseed.com/voice-linter
TLS valid
Negotiated TLS 1.3 with TLS_AES_128_GCM_SHA256 .
| Subject | Issuer | Valid from | Valid until | Key | Signature | Serial |
|---|---|---|---|---|---|---|
| CN=mcp.modernmustardseed.com | CN=YR2,O=Let's Encrypt,C=US | 11 Oct 2026 | 9 Jan 2027 | RSA 2048 | SHA256-RSA | 5037aab1b1b95f22d0713db17fad3a7354f |
| SANs: mcp.modernmustardseed.com | ||||||
| CN=YR2,O=Let's Encrypt,C=US (CA) | CN=Root YR,O=ISRG,C=US | 3 Sept 2025 | 2 Sept 2028 | RSA 2048 | SHA256-RSA | 4ebd24947e24d394802d84a52fd5b319 |
| CN=Root YR,O=ISRG,C=US (CA) | CN=ISRG Root X1,O=Internet Security Research Group,C=US | 13 May 2026 | 2 Sept 2032 | RSA 4096 | SHA256-RSA | f24b6d17f9d9ad7cb1c9fea78782699f |
Background: What to check on a remote MCP endpoint →
DNSSEC insecure
Validation of mcp.modernmustardseed.com. — Not signed
| Zone | DS | Keys | Algorithms | Outcome |
|---|---|---|---|---|
| . | trust_anchor | 20326, 38696 | 8, 8 | Verified |
| com. | present | 19718 | 13 | Verified |
| modernmustardseed.com. | absent | Unsigned (proven) parent-signed NSEC/NSEC3 proves an unsigned delegation |
Authentication No authorisation required
The endpoint answered without asking for a token. Anyone who knows the URL can reach it.
| Result | No authorisation required |
|---|---|
| HTTP status | 200 |
| Header | Value |
|---|---|
| strict-transport-security | max-age=63072000 |
| x-content-type-options | nosniff |
| x-frame-options | SAMEORIGIN |
| referrer-policy | strict-origin-when-cross-origin |
| permissions-policy | camera=(), microphone=(), geolocation=() |
Background: How OAuth 2.1 works in the 2026 MCP spec →
Transports 2 probes
| Transport | URL | Outcome | Status | Location |
|---|---|---|---|---|
| streamable-http | https://mcp.modernmustardseed.com/voice-linter | Verified | 200 | |
| http (plaintext) | http://mcp.modernmustardseed.com/voice-linter | HTTPS enforced | 308 | https://mcp.modernmustardseed.com/voice-linter |
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 →
explain_lint_rule Explain a lint rule ~87
Explain one Voice Agent Linter rule by id: why it exists, a bad and a good example, the fix, the platforms it applies to, and its sources with the date each was read. Static reference, no network access.
| Name | Type | Req | Description |
|---|---|---|---|
| rule_id | string | yes | The rule id, for example no-live-date, vapi-nested-item-enum or no-ai-disclosure. |
No output schema declared.
No examples provided.
lint_voice_agent Lint a voice agent ~508
Check a phone voice agent’s system prompt and, optionally, its config JSON (Vapi assistant, Retell agent or LLM, ElevenLabs agent, or OpenAI Realtime session) against rule-based checks learned on live calls. Finds: no live date and dates without a year; phone numbers, emails, URLs, hyphen ranges and long numbers the voice will misread; no spelling protocol or bare-letter spelling; instructions to pass as human, missing AI disclosure and missing recording notice; scripted tool start lines, stall phrases and silent or long openers; tools with no description, untyped or undescribed parameters, undefined required fields, unformatted date parameters and unstated results; Vapi nested item enums, flat analysisPlan keys, disabled plans and plans without the transcript; ElevenLabs Turbo stutter risk; no transfer or callback path and no end-call; placeholders, secrets, very long prompts and contradictory always and never rules. Each finding has a rule id, severity, the exact line (and JSON path for config), an excerpt, a specific message and the fix; disclosure and recording rules carry their legal citations with the date read. Returns a 0 to 100 score and a verdict. Do not paste credentials: API keys, bearer tokens, passwords and the values of secret-named config fields (apiKey, secret, token, password, credentials, Authorization) are stripped from the input before any check runs and replaced with "[secret removed]", so they are never read, returned, logged or stored; the output says how many were removed. No model reads the input and nothing is stored. Informational, not legal advice.
| Name | Type | Req | Description |
|---|---|---|---|
| config_json | string | – | The agent’s config as a JSON string, exactly as the platform exports it (remove keys first; any left are stripped before checking): a Vapi assistant, a Retell agent and/or LLM (or {"agent": ..., "llm… |
| first_message | string | – | The opening line the agent speaks, when it is not in the config. |
| min_severity | string | – | Only return findings at or above this severity: critical, high, medium or low. |
| platform | string | – | Which platform the config is for. "auto" detects it from the JSON. |
| system_prompt | string | – | The agent’s system prompt, as plain text. Optional when config_json contains it. |
No output schema declared.
No examples provided.
list_lint_rules List lint rules ~98
List every Voice Agent Linter rule with its id, title, default severity, category, what it reads (prompt, config or both) and the platforms it applies to. Filter by platform or category. Static reference, no network access.
| Name | Type | Req | Description |
|---|---|---|---|
| category | string | – | Only rules in this category. |
| platform | string | – | Only rules that apply to this platform: vapi, retell, elevenlabs or openai_realtime. |
No output schema declared.
No examples provided.
How do I install the Voice Agent Linter MCP server?
Voice Agent Linter is a hosted endpoint at https://mcp.modernmustardseed.com/voice-linter, 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 · mcp.modernmustardseed.com
claude mcp add --transport http com-modernmustardseed-voice-linter 'https://mcp.modernmustardseed.com/voice-linter'
What is the Voice Agent Linter MCP server?
Voice Agent Linter is an MCP server listed in the public MCP registry as com.modernmustardseed/voice-linter. Lints a phone voice agent prompt and platform config before real callers reach it. This page covers its hosted endpoint (https://mcp.modernmustardseed.com/voice-linter).
Is the Voice Agent Linter MCP server safe to use?
Voice Agent Linter scores 74 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 Voice Agent Linter MCP server expose?
Voice Agent Linter exposes 3 tools: lint_voice_agent, list_lint_rules, explain_lint_rule. Their descriptions and schemas cost roughly 693 tokens of context every time the server is loaded.
Does the Voice Agent Linter MCP server require authentication?
No. We connected to Voice Agent Linter without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.
Is the Voice Agent Linter MCP server still maintained?
Voice Agent Linter is still listed as active in the MCP registry. We last reached this channel on 17 October 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.