# Voice Agent Linter (remote · mcp.modernmustardseed.com)

Lints a phone voice agent prompt and platform config before real callers reach it.

- Trust score: 74/100 (medium)
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-10-17

## Components

- remote · `mcp.modernmustardseed.com`: 74/100 (this document), [markdown](https://verifymcp.io/servers/com-modernmustardseed-voice-linter/voice-linter.md), [page](https://verifymcp.io/servers/com-modernmustardseed-voice-linter/voice-linter)

## Channel facts

- Endpoint: `https://mcp.modernmustardseed.com/voice-linter`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.0.0`

## Trust breakdown

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. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-10-17.

- **Endpoint Security**: 80/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - No authorisation is required to call this server. Every tool declares its destructiveHint and none is destructive, so open access doesn't expose one.
  - HTTPS is enforced; there's no plaintext access path.
  - The HSTS (Strict-Transport-Security) header is present.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 64/100
  - AI-judged instruction clarity (excellent).
  - 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.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 17/100
  - Stability observed for 5 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 3 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 4 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a current MCP spec version (2026-07-28).

## Install

### 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.

### Claude

```bash
claude mcp add --transport http com-modernmustardseed-voice-linter 'https://mcp.modernmustardseed.com/voice-linter'
```

### Cursor

```json
{
  "mcpServers": {
    "com-modernmustardseed-voice-linter": {
      "url": "https://mcp.modernmustardseed.com/voice-linter"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "com-modernmustardseed-voice-linter": {
      "type": "http",
      "url": "https://mcp.modernmustardseed.com/voice-linter"
    }
  }
}
```

### Codex

```toml
[mcp_servers.com-modernmustardseed-voice-linter]
url = "https://mcp.modernmustardseed.com/voice-linter"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "com-modernmustardseed-voice-linter": {
      "type": "remote",
      "url": "https://mcp.modernmustardseed.com/voice-linter",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add com-modernmustardseed-voice-linter --url 'https://mcp.modernmustardseed.com/voice-linter' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  com-modernmustardseed-voice-linter:
    url: "https://mcp.modernmustardseed.com/voice-linter"
```

### Netclaw

```json
{
  "McpServers": {
    "com-modernmustardseed-voice-linter": {
      "Transport": "http",
      "Url": "https://mcp.modernmustardseed.com/voice-linter"
    }
  }
}
```

### Vellum

```bash
assistant mcp add com-modernmustardseed-voice-linter -t streamable-http -u 'https://mcp.modernmustardseed.com/voice-linter'
```

### Other

```json
{
  "mcpServers": {
    "com-modernmustardseed-voice-linter": {
      "type": "http",
      "url": "https://mcp.modernmustardseed.com/voice-linter"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-10-17 (score 74, +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.

### 2026-10-14 (score 73, +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.

### 2026-10-13 (score 72, 0)

- [functional improvement] Stability: unverified → 0.03

### 2026-10-12 (score 72)

First indexed and scored.

## MCP tools (3)

### `lint_voice_agent` (~508 tokens)

Lint a voice agent

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.

Input parameters:

- `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.

### `list_lint_rules` (~98 tokens)

List lint rules

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.

Input parameters:

- `category` (string): Only rules in this category.
- `platform` (string): Only rules that apply to this platform: vapi, retell, elevenlabs or openai_realtime.

### `explain_lint_rule` (~87 tokens)

Explain a lint rule

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.

Input parameters:

- `rule_id` (string, required): The rule id, for example no-live-date, vapi-nested-item-enum or no-ai-disclosure.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/com-modernmustardseed-voice-linter/voice-linter#diagnostics

## Score history

- 2026-10-17: 74
- 2026-10-16: 73
- 2026-10-15: 73
- 2026-10-14: 73
- 2026-10-13: 72
- 2026-10-12: 72

## Common questions

### 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.

## Links

- Remote endpoint: https://mcp.modernmustardseed.com/voice-linter
- Website: https://mcp.modernmustardseed.com/docs/voice-linter
- Changelog RSS feed: https://verifymcp.io/servers/com-modernmustardseed-voice-linter/voice-linter.xml
- Changelog JSON feed: https://verifymcp.io/servers/com-modernmustardseed-voice-linter/voice-linter.json
- HTML version of this page: https://verifymcp.io/servers/com-modernmustardseed-voice-linter/voice-linter