From zero to "the agent placed the call".

Install the npm package

Global install gets you the crixin binary in every terminal — voice lives under crixin voice — plus instant access from your AI host via npx.

npm i -g crixin

# or, no global install — npx fetches on demand:
npx -y crixin voice help

Wire up Twilio credentials

Crixin doesn't ship with credentials baked in. You need a Twilio account (free trial gives you a sandbox number), then export three env vars:

export TWILIO_ACCOUNT_SID=ACxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
export TWILIO_AUTH_TOKEN=your_auth_token
export TWILIO_PHONE_NUMBER=+15555550100

# Optional — only needed if you call transcribe_call
export DEEPGRAM_API_KEY=...

Verify with the doctor:

crixin voice doctor

Wire it into your AI host

Same npm package, same stdio MCP transport. The host-specific config is one line each.

claude mcp add crixin-voice -- \
  npx -y crixin voice mcp

// ~/.cursor/mcp.json
{
  "mcpServers": {
    "crixin/voice": {
      "command": "npx",
      "args": ["-y", "crixin", "voice", "mcp"]
    }
  }
}

# ~/.codex/config.toml
[mcp_servers.crixin-voice]
command = "npx"
args = ["-y", "crixin", "voice", "mcp"]

// ~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "crixin/voice": {
      "command": "npx",
      "args": ["-y", "crixin", "voice", "mcp"]
    }
  }
}

Place the first call

Simplest possible smoke test — the CLI bypasses MCP and calls Twilio directly. Replace the destination with your own number.

crixin voice call +15555550100 "Hello, this is a test call from Crixin Voice."

You should see:

Call placed: CA94e1d8…3a02 → queued

Then ask your AI host the same question and watch it call make_call on your behalf.

If something didn't work

• "Missing TWILIO_ACCOUNT_SID." — env vars aren't reaching the AI host. On macOS, GUI apps don't see ~/.zshrc. Use launchctl setenv or run the host from a terminal.
• "E.164 required." — your TWILIO_PHONE_NUMBER needs the leading + and country code, e.g. +15555550100.
• Call queued forever. — destination might be in a region your Twilio account hasn't enabled. In Console → Voice → Geographic Permissions, allow the country.
• Recipient hears silence. — Twilio Trial accounts require destination numbers to be verified first. Verify in Console → Phone Numbers → Verified Caller IDs.