Open a Voice Bridge session: a live phone call where YOUR LLM is the brain. Sats4AI provides PSTN + streaming STT + TTS as composable primitives. You decide when to speak (call voice_bridge_say), you read transcripts as they arrive (call poll_voice_bridge), you close the call when done (call end_...
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AI agents use open_voice_bridge to create or modify resources in Sats4AI - Bitcoin-Powered AI Tools. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call open_voice_bridge repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Sats4AI - Bitcoin-Powered AI Tools.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"open_voice_bridge": {
"limits": [
{
"counter": "open_voice_bridge_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Sats4AI - Bitcoin-Powered AI Tools policy for all 49 tools.
These attack patterns abuse exactly the kind of access open_voice_bridge gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Open a Voice Bridge session: a live phone call where YOUR LLM is the brain. Sats4AI provides PSTN + streaming STT + TTS as composable primitives. You decide when to speak (call voice_bridge_say), you read transcripts as they arrive (call poll_voice_bridge), you close the call when done (call end_voice_bridge). Unused deposit time is refunded via LNURL-withdraw. Use this when you want to keep your conversation context private and drive each turn yourself. When NOT to use: not for fully-managed agent-style calls where we handle the brain (use ai_call). Not for one-shot TTS broadcasts or IVR playback (use place_call). Not when live transcript polling adds no value — the per-turn overhead isn't worth it. Privacy: transcripts held in memory only, garbage-collected 30 minutes after the call ends; call audio is never persisted. Pay with Bitcoin Lightning — no telecom account, no signup. Requires create_payment with toolName='voice_bridge_open', phoneNumber, durationMinutes. Deposit: ~10 sats/min US, ~30 intl, ~80 rare.. It is categorised as a Write tool in the Sats4AI - Bitcoin-Powered AI Tools MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Sats4AI - Bitcoin-Powered AI Tools MCP server in PolicyLayer and add a rule for open_voice_bridge: 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 Sats4AI - Bitcoin-Powered AI Tools. Nothing to install.
open_voice_bridge is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the open_voice_bridge 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.
Set action: deny in the PolicyLayer policy for open_voice_bridge. 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.
open_voice_bridge is provided by the Sats4AI - Bitcoin-Powered AI Tools MCP server (cnghockey/sats4ai-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 49 Sats4AI - Bitcoin-Powered AI Tools tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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