Which tools should a phone agent have?

As few as do the job. `set_time_alarm` and `list_my_alarms` cover most calls; add more only when callers need them.

Can a caller add friends to an alarm?

Yes, by LFG Alarm username, after confirming who. On a phone call that means the agent reads the names back and waits for a yes.

Does the alarm ring during the call?

No. It rings on the phone with the LFG Alarm app, at the time set. Time alarms are real alarms on both iPhone and Android and ring through silent mode.

Does LFG Alarm hear the call?

No. LFG Alarm only receives what the agent sends when it uses LFG Alarm's tools, never the audio.

Connect LFG Alarm to Retell

Before you start

Get the LFG Alarm app on your phone from Google Play or the App Store, and sign in. The Retell agent makes the alarms; the app is what rings them.
A personal key, since a phone agent cannot do a sign-in. Make one below.

A key acts as you. With one key in the header, every caller sets alarms on the key owner's phone, whoever is calling. That is right for your own line or a small business where you are the one to wake. It is wrong for a public line where callers expect their own alarms. Retell has a way round this, below: it can pass each caller's own key.

Make a key

In LFG Alarm, open Settings > Connected AI apps, on lfg.gm or in the app.
Tap Make a key, name it after the agent (for example "Retell front desk"), and tap Make the key.
The key is shown once, with Copy and Done: "Copy it now. It won't be shown again." Copy it, keep it ready for the next step, then tap Done.
It now shows in the list as Personal key, with when it was last used.

The screen says it plainly: "For an AI app that asks for a key instead of a sign-in, like Manus, a coding agent or your own script. A key acts as you, so keep it out of any agent other people use."

Keys start with lfg_pat_, work only at the LFG Alarm MCP server, and you can have up to 20. A key has the same plan limits as signing in.

Connect it

Single or multi-prompt agent:

Open the agent and find MCPs, then click Add MCP.
Name: LFG Alarm. URL: https://mcp.lfg.gm (no /mcp on the end). Retell uses Streamable HTTP, which LFG Alarm speaks.
Leave Timeout at its default unless calls cut off.
Under Headers, add a key Authorization with the value Bearer lfg_pat_... (the word Bearer, a space, then your key). Leave Query Parameters empty.
Click Save, then Add Tools. Retell only exposes the tools you pick, one by one. For most phone agents two are enough: set_time_alarm and list_my_alarms. Add turn_alarm_on_off if callers should be able to cancel.
Optional: turn on Talk While Waiting so the agent says "setting that now" instead of going quiet. Save.
In the agent's prompt, say when to call each tool: "When the caller asks to be reminded or woken at a time, call set_time_alarm, then read back the time it rings."

Conversation flow: add an MCP node, set the same URL and header, and pick the one LFG Alarm tool that node should call. Response variables can carry the ring time into the next node.

Picking tools one by one keeps calls quick: the model only reads the tools you chose, not all of LFG Alarm's.

Each caller's own key

Retell lets header values use dynamic variables, filled in when each call starts. So instead of your key, the header can be:

Authorization: Bearer {{lfg_key}}

and your system passes lfg_key for each call (for example in the dynamic variables you send when you start an outbound call, or from your inbound call webhook). The alarm then lands in that caller's own LFG Alarm account and rings their phone, not yours.

This solves the shared-key problem, but it needs something behind it: each caller must have their own LFG Alarm account, and must have made a key and given it to you to store safely, keyed to their phone number or customer record. It suits a small group you know, such as a team or members who signed up. A key is shown to its owner once, so they paste it into your system themselves; never ask callers to read a key out on a call.

What fits

Your own call handler. It takes a call while you are on site and sets "Call the supplier back" for 7:00 on your phone.
A small team line. A morning-shift alarm made a friends alarm, with the team added, so one request rings everyone at 5:30.
Members with their own keys. A club's line where each member's key is passed by variable, so "wake me at 6 for the ride" sets the alarm on the caller's own phone.

Try it

Once it is connected, call your agent and say:

try this

Have your AI agent make it.

Paste this into ChatGPT, Claude, Grok or any AI agent that can add a connector, not into the LFG Alarm app. The setup steps come with it: get the LFG Alarm app, connect it to your agent once, and your agent makes the alarm in your account.

Set an LFG Alarm for 7:00 tomorrow morning called "Call the supplier", and tell me when it goes off.

Already have the LFG Alarm app and connected it to your AI agent?

Why it works. One time alarm and the time read back, the shortest proof on a phone call that the header and the tool both work.

More ideas: "What alarms do I have tomorrow?", "Turn off my 7am alarm", or "Make a friends alarm for Saturday at 8 called Hike and add [username]". Through a key, LFG Alarm can set time, price, post, event and anything alarms, pick a sound or a look from the library, and add your friends or a whole group once you confirm. Each alarm comes back with its link, a share picture with a QR code and a message ready to send. Wallet and trader alarms are made in the app. See Using LFG Alarm from your AI agent.

If it does not work

Save fails or no tools to pick. Check the URL is exactly https://mcp.lfg.gm, and that the header value starts with Bearer and a space.
The agent says it set an alarm but none appears. Check the tool was added under Add Tools, and that the prompt says when to call it.
Per-caller keys do not work. Check the variable name in the header matches the one you pass, and that the value is the whole key.
It refuses an alarm. A key has the same plan limits as signing in. For plans and pricing, go to lfg.gm.
Still stuck? Write to us from the support page.

Disconnect

In LFG Alarm, open Settings > Connected AI apps and tap Disconnect beside the key. It stops working at once. You can also remove the MCP from the agent in Retell. Your alarms stay in your account and keep ringing.

Learn more

Sources and further reading

LFG Alarm is not affiliated with Retell AI.