wave_start_captions · WAVE MCP Server MCP: Risk & Policy

WHAT IT DOES

What wave_start_captions does on WAVE MCP Server

AI agents invoke wave_start_captions to trigger actions in WAVE MCP Server. 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 wave_start_captions needs a policy

This tool triggers an external service (real-time transcription/captioning) on a stream, making it an Execute action rather than a simple Read. While not destructive or financial in nature, it modifies the state of a live stream by activating a feature.

From the tool's definition Tool name 'wave_start_captions' and description 'Start real-time captions/transcription on a stream' indicate an action that initiates an external operation (caption/transcription service) on a live stream, which is irreversible once started and depends on…

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

wave_start_captions Rate-limited

wave_start_captions 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": {
    "wave_start_captions": {
      "limits": [
        {
          "counter": "wave_start_captions_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 WAVE MCP Server, so you can run agents against it safely.

FAQ

Questions about wave_start_captions

What does the wave_start_captions tool do? +

Start real-time captions/transcription on a stream. It is categorised as a Execute tool in the WAVE MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on wave_start_captions? +

Register the WAVE MCP Server MCP server in PolicyLayer and add a rule for wave_start_captions: 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 WAVE MCP Server. Nothing to install.

What risk level is wave_start_captions? +

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

Can I rate-limit wave_start_captions? +

Yes. Add a rate_limit block to the wave_start_captions 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 wave_start_captions completely? +

Set action: deny in the PolicyLayer policy for wave_start_captions. 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 wave_start_captions? +

wave_start_captions is provided by the WAVE MCP Server MCP server (wave-av/mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.