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open_voice_bridge

Open a live voice bridge session for private, LLM-driven phone calls. Control each turn, pay with Bitcoin, and get refunded for unused time.

Instructions

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.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
paymentIdYesValid payment ID from create_payment (toolName=voice_bridge_open)
phoneNumberYesDestination phone number in E.164 format (e.g., +14155550100)
languageNoBCP-47 language tag (default en-US). See /api/l402/voice-bridge/coverage for the matrix.
durationMinutesNoDeposit for N minutes, 2-30 (default 3). Unused time refunded.
codecNoPCMU 8kHz (default, universal) or L16_16000 for HD voice when both endpoints support it
sttEnabledNoDefault true. Set false for TTS-only broadcast calls.
ttsEnabledNoDefault true. Set false to bring-your-own-audio via voice_bridge_say.
refundAddressNoLightning address for automatic refund of unused time
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Discloses session lifecycle (speak, poll, end), refund mechanism, privacy policy (transcripts in memory, 30-min GC, no audio persistence), and payment method (Bitcoin Lightning). All critical behavioral traits covered despite no annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Long but justified given complexity; front-loaded with purpose and usage, then details. Every sentence adds value, no waste. Could slightly condense, but effective.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers prerequisites, payment, refund, privacy, and interaction pattern. No output schema, but description sufficiently explains the tool's role in a multi-step process. Missing explicit return value, but minor.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema covers 100% of parameters, baseline 3. Description adds context for paymentId (from create_payment), phoneNumber format, durationMinutes as deposit, refundAddress for refund, and language/codec options, raising usefulness.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

Clearly states 'Open a Voice Bridge session: a live phone call where YOUR LLM is the brain.' with specific verb (open) and resource, and distinguishes from siblings ai_call and place_call.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use (privacy, drive turns), when not to use (managed calls, TTS broadcasts, low-value polling), and prerequisites (create_payment).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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