# MCP Server

The MCP (Model Context Protocol) server lets any MCP-compatible AI assistant
control the Hold Slayer gateway. Built with [FastMCP](https://github.com/jlowin/fastmcp),
it is mounted on the FastAPI app at **`/mcp/`** (trailing slash) over
**streamable HTTP** and authenticates with an owner-minted Personal Access Token
(`hs_pat_…`) — the same owner-only auth as the REST API and WebSocket. Auth is
enforced by an ASGI guard (`_owner_only_mcp` in `main.py`) that resolves the
bearer to the owner; a Casdoor JWT also works, but MCP clients can't refresh one,
so a PAT is the intended credential.

## Overview

An AI assistant connects to the MCP endpoint and gains access to 15 tools and
3 resources for placing calls, checking status, sending DTMF, getting
transcripts, and managing call flows. The assistant can orchestrate an entire
call through natural language.

`make_call` places a **real PSTN call** that may incur charges; emergency
numbers are always refused, and the concurrent-call cap applies.

## Tools

### make_call

Place an outbound call through the SIP trunk.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `number` | string | Yes | Phone number to call (E.164 format) |
| `mode` | string | No | `direct`, `hold_slayer`, or `ai_assisted` (default: `direct`) |
| `intent` | string | No | What you want to accomplish on the call |
| `call_flow_id` | string | No | ID of a stored call flow to follow |
| `device` | string | No | Device to transfer to when a human is detected |

Returns: call ID and initial status.

### get_call_status

Check the current state of a call — status, duration, hold time, current
audio classification, recent transcript.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | The call to check |

### transfer_call

Transfer an active call to a registered device.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | The call to transfer |
| `device` | string | Yes | Device ID or type to ring |

### hangup

Hang up an active call.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | The call to hang up |

### list_active_calls

List all calls currently in progress. No parameters.

### send_dtmf

Send touch-tone digits on an active call (manual IVR navigation).

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | The call to send digits on |
| `digits` | string | Yes | DTMF digits (e.g., `"1"`, `"123#"`) |

### get_call_transcript

Get the full transcript of an active call.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | The call to get the transcript for |

### get_call_recording

Get recording metadata (path, duration) for a persisted call.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | The call to look up |

### get_call_summary

Stored summary, action items, and sentiment for a persisted call.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | The call to look up |

### search_call_history

Search past call records.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `phone_number` | string | No | Filter by phone number (partial match) |
| `intent` | string | No | Filter by intent text (partial match) |
| `limit` | int | No | Max results (default: 10) |

### get_call_flow

Look up the stored IVR call flow for a phone number.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `phone_number` | string | Yes | Number to look up (E.164) |

### create_call_flow

Store a new IVR call flow by hand.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `name` | string | Yes | Human-readable name |
| `phone_number` | string | Yes | Phone number (E.164) |
| `steps_json` | string | Yes | JSON array of call flow steps |
| `notes` | string | No | General notes |

### learn_call_flow

Build (or refine) a reusable IVR call flow from a completed hold-slayer
exploration call. Exploration calls record every IVR prompt heard and DTMF
sent; this turns those discoveries into a stored flow so the next call
navigates directly.

| Param | Type | Required | Description |
|-------|------|----------|-------------|
| `call_id` | string | Yes | A completed call that ran in exploration mode |
| `company_name` | string | No | Company name for labeling a new flow |

### list_devices

List registered devices and their online/offline status. No parameters.

### gateway_status

Trunk registration, device count, active calls, engine mode. No parameters.

## Resources

| Resource URI | Description |
|-------------|-------------|
| `gateway://status` | Current gateway status — trunk registration, active calls |
| `gateway://call-flows` | List of all stored call flows |
| `gateway://active-calls` | All active calls with current status |

## Connecting an AI Assistant

Claude Code:

```bash
claude mcp add hold-slayer --transport http http://localhost:8000/mcp/ \
  --header "Authorization: Bearer hs_pat_..."
```

Generic MCP client configuration:

```json
{
  "mcpServers": {
    "hold-slayer": {
      "url": "http://localhost:8000/mcp/",
      "headers": {"Authorization": "Bearer hs_pat_..."}
    }
  }
}
```

## Example Conversation

**User:** "Call Chase Bank and dispute the Amazon charge from December 15th"

**Assistant actions:**

1. Calls `make_call(number="+18005551234", mode="hold_slayer", intent="dispute Amazon charge Dec 15th", call_flow_id="chase-bank-main")`
2. Receives `call_id: "call_abc123"`
3. Polls `get_call_status("call_abc123")` periodically
4. Status progression: `initiating` → `ringing` → `connected` → `on_hold`
5. Tells user: "I'm on hold with Chase Bank. Currently 4 minutes in. I'll let you know when someone picks up."
6. Status changes to `transferring` — human detected!
7. Tells user: "A live agent just picked up. I'm transferring the call to your desk phone now. Pick up!"
8. After the call, calls `learn_call_flow("call_abc123", company_name="Chase Bank")` to save the IVR path for next time.