tts_speak · Tts MCP: Risk & Policy

WHAT IT DOES

What tts_speak does on Tts

AI agents invoke tts_speak to trigger actions in Tts. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why tts_speak needs a policy

Text-to-speech synthesis is an external operation execution. While the tool has safety constraints (voice/model/language/format locked per profile, limiting parameter abuse), it still executes a third-party service call with user-supplied text and audio parameters. This is Execute rather than Write because the tool invokes an external service to produce output rather than modifying stored data.

From the tool's definition Tool 'tts_speak' generates speech synthesis output by invoking Google Cloud Text-to-Speech with adjustable parameters (speaking rate, pitch). This triggers external API operations whose effects (audio generation, potential playback) depend on input arguments.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

tts_speak Rate-limited

tts_speak stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "tts_speak": {
      "limits": [
        {
          "counter": "tts_speak_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Tts, so you can run agents against it safely.

FAQ

Questions about tts_speak

What does the tts_speak tool do? +

Generate speech with fixed voice/model/language/format and adjustable speaking rate and pitch. It is categorised as a Execute tool in the Tts MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on tts_speak? +

Register the Tts MCP server in PolicyLayer and add a rule for tts_speak: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Tts. Nothing to install.

What risk level is tts_speak? +

tts_speak is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit tts_speak? +

Yes. Add a rate_limit block to the tts_speak rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block tts_speak completely? +

Set action: deny in the PolicyLayer policy for tts_speak. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides tts_speak? +

tts_speak is provided by the Tts MCP server (that-lucas/tts-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.