How to give Meta Muse an API key safely

When you connect Meta Muse to a service that is not in Meta's directory, that service gives you a key, and Muse needs it to act on your behalf. The single rule is: the key goes into Muse's Secure Credentials Store, never into the chat.

When you do it that way, the AI itself never handles the real key. It works with a stand-in value, and the real secret is swapped in at the last moment by a separate part of Meta's system that handles permissions. This page explains what that means in plain terms, how to do it, and how to undo it.

What an API key is, in one paragraph

It is a long password that belongs to a program rather than to a person. Not your Facebook password, not your email password. It gives the holder permission to do one specific thing with one specific service. Ours lets Muse send mail and faxes from your account, book appointments, and spend your credits. Nothing else. If someone stole it, they could mail letters and run down your balance. They could not read your email, see your photos, or get into your bank.

Where it goes

Into the Secure Credentials Store. Muse offers this by itself when a connector needs a key. You will see a field clearly meant for a secret, with a name attached. Ours is NOERRANDS_API_KEY.

Not into the chat. If Muse ever asks you to type a key into the conversation, say no and tell it to use the store. Our paste prompt says so up front, and you can read it at the bottom of this page.

Why the store beats the chat

The obvious reason. Things typed into a chat live in the chat history. They can be scrolled back to, screenshotted, and read by anyone you hand your phone to.

The real reason. Meta's design is that the model never receives the key at all. It gets a placeholder, and a separate process substitutes the real secret at the network boundary when a request goes out.

Why that matters: AI agents read web pages, and some pages contain hidden text trying to trick the agent into revealing secrets. If the model never had the key, there is nothing to hand over. The protection does not depend on the AI being careful. It depends on the AI not having the thing.

Meta's engineers have called attempts to extract secrets this way futile for exactly this reason. We would put it less confidently. The design is sound, and it is why we are comfortable recommending this to people who do not write software.

Step 1: Get the key

Go to https://noerrands.com/get-key and enter your email. We show the key once. If you lose it, make a new one; that costs nothing.

Choose read if you only want Muse to check addresses, prices and past sends. Choose read and write if you want it to send.

Step 2: Have it ready to paste

Do not email it to yourself and do not put it in a note app. Copy, use, done.

Step 3: Paste the setup prompt into Muse

The prompt is at the bottom of this page. It tells Muse to store the key under NOERRANDS_API_KEY and never to print, log or echo it.

Step 4: Put the key in the Secure Credentials Store

When Muse asks for the key, paste it into the store, under the name NOERRANDS_API_KEY. Not into the chat.

Step 5: Approve the connection

Muse asks permission to reach our domain before anything leaves its machine. Approve it once. Then clear your clipboard by copying anything else.

How to take it back

Two switches. Know both.

On Muse's side. In Muse's settings, find the stored credential and remove it. Muse can no longer use it, though the key still exists.

On our side. Email support@noerrands.com and we revoke it. The key stops working immediately for everyone, including Muse. Do this if you think someone has seen it.

Revoking is free and unlimited. Make a new key straight afterwards if you still want the connector. Nobody here will be annoyed with you for rotating keys. If you think you have a reason to, you have a reason to.

Questions people actually ask

Can Muse see my key?

The model does not handle the real value. It works with a stand-in and the real key is substituted at the network edge.

Can Meta see my key?

Meta stores it. It is Meta's credential store. If you are not comfortable with that, the answer is not to use custom connectors.

Is this my Facebook password?

No. One service, one job.

What is the worst case if it leaks?

Someone mails letters until your credits run out. Annoying, not catastrophic. Email support@noerrands.com and we revoke it.

Should I use a read-only key?

If you only want Muse to check prices and look up past sends, yes. Ask for a read key at https://noerrands.com/get-key and add a sending key later.

Does this mean the connector is safe?

It means your key is handled well. It does not mean anybody reviewed the connector. Custom connectors are not reviewed by Meta, ours included, and Meta shows you a notice saying so. More in how custom connectors work.

Will Muse spend my credits without asking?

No. It checks the address, prices the job, shows you everything, then waits. United States addresses only. A letter starts at $2.49, and credits are bought as $2.49 for a single letter, or $10.00 for $12.50 of credit (one free letter), $25.00 for $32.50 of credit (three free letters) and $50.00 for $67.50 of credit (seven free letters); every pack credits more than it costs.

The prompt to paste into Muse

Copy the whole block and paste it into Muse as one message.

Build a custom connector for No Errands. One API key covers three services:
printed mail (letters and postcards), fax, and appointment booking.

1. Read these three connector briefs and follow them exactly:
   https://noerrands.com/connectors/muse.md
   https://noerrands.com/connectors/fax/muse.md
   https://noerrands.com/connectors/booking/muse.md

2. Store my API key in the Secure Credentials Store as NOERRANDS_API_KEY.
   The same key works for all three. Never print, log, echo, or repeat it,
   not even partially.
   Send it as the header: Authorization: Bearer <NOERRANDS_API_KEY>

3. Prefer the MCP endpoints (streamable HTTP):
   https://api.noerrands.com/c/mail/mcp
   https://api.noerrands.com/c/fax/mcp
   https://api.noerrands.com/c/booking/mcp
   If you use the REST APIs instead, each brief links its OpenAPI document.

4. Before you mail anything, fax anything, or book anything, show me exactly
   what will happen, what it costs, and who it goes to, and wait for my
   explicit approval. Never act without asking me first.

5. Save this as a reusable skill called "Mail, fax and bookings".

Plain text version: /muse-prompt.txt. Step by step: send a letter with Meta Muse, or all the how-tos.