The handbrake: how to stop Claude sending anything to a client without your say-so
Before you let SI near anything a client will see, put a handbrake on it. One rule, one gate, and one prompt that makes Claude stop and show you before it sends.
The day my AI nearly texted my whole database twice.
That's the moment this rule stopped being a nice idea and became the most important part of my system. Today's post is about the handbrake: one rule that sits between Claude and anyone outside your business.
By this point in the series you've given Claude jobs, connected it to your files and saved jobs as Skills. It's doing real work now. And the more real work it does, the more it matters what happens at the edge, where something leaves your desk and lands in a client's phone or inbox.
What the handbrake is
It's simple. Anything that reaches a client goes through one gate.
Not three different checks in three different places. One gate, every time. Before a message goes out, the gate asks a few plain questions:
- Is this a duplicate? Has the same message already gone to this person?
- What time is it? Is this a reasonable hour to be contacting someone?
- Has this been sent before? Is it repeating something that already went out?
If the answer to any of those is wrong, it doesn't go. Mine has stopped 8,760 texts that would have been duplicates.
That number isn't there to impress anyone. It's there to show how often a well-meaning system will try to do the same thing twice. Software repeats itself. A job runs again, a list gets loaded twice, a step gets retried. None of that is a problem until the thing being repeated is a text to a real person.
Why it matters for an agent
Most of what we send is personal. An appraisal confirmation. A price update to a vendor. A follow-up to someone who came through an open home. A market update to a database of past clients.
Get one of those wrong and it's awkward. Send it twice and it looks careless. Send it to the whole database at the wrong hour and you've spent years of goodwill in one evening.
Clients don't see your system. They only see what arrives. So the rule has to be about what arrives.
The good news is you don't need a complicated setup to start. You need one instruction, written down, that Claude follows every time.
Draft, never send
The rule written into my instructions comes down to this: never send, only draft.
Claude can write the message. It can pick who it should go to, check the details and lay it all out. What it doesn't do is press send on its own. It stops, shows me exactly what it's about to do, and waits.
That one change turns Claude from something that acts on your behalf into something that prepares and hands over. You stay the last set of eyes on anything with your name on it.
Over time you can build checks on top of that, like the duplicate and time-of-day checks above. But the foundation is the same. Nothing outward-facing happens without a yes.
The Day 16 prompt
Before you send, post or change anything that a client or the public will see, stop and show me exactly what it is. Never send anything on your own.
Here's what each part is doing.
"Before you send, post or change anything" covers the three ways something can go wrong in public. Sending is texts and emails. Posting is social media and websites. Changing is the quiet one, like editing a listing or updating something a client can already see.
"that a client or the public will see" draws the line in the right place. Claude can still tidy your files, draft notes and sort your lists without stopping every two minutes. The handbrake only applies where it counts.
"stop and show me exactly what it is" means you see the real thing, not a summary. The actual words, the actual recipient, the actual post. If it's going to ten people, you see that it's ten people.
"Never send anything on your own" closes the door. Even if Claude thinks it has permission, even if it's sure, it waits for you.
Try it yourself
- Pick one narrow folder. Use the folder for a single job, like drafting follow-ups after an open home. Copies of files, not originals, and not your whole computer.
- Put the prompt where it will always apply. If you're working in a project, add it to the project's instructions so every conversation in that project starts with it. If you're not, paste it as the first line of the conversation.
- Give Claude a job that ends in a message. For example: "Draft a follow-up text for each person in this list. Show me your plan first."
- Read what comes back. Check the wording, the names and the number of messages. Look for anything doubled up.
- Approve or correct. Say yes to the ones that are right, fix the ones that aren't, and send them yourself.
- Check your settings. If you've connected Claude to anything that can send email, post or message on your behalf, look at how it asks for permission in the app's settings. Keep approvals on for anything that sends, spends or deletes.
Do this for a week and you'll start to notice the kinds of mistakes it would have made. That's useful. It tells you which checks to add to your own gate.
Building your own gate
Once the basic rule is working, you can ask Claude to add simple checks before it shows you anything. A few that make sense for most agents:
- Duplicate check. "Before showing me any message, check whether the same person already has an identical message in this list."
- Time check. "Flag anything that would go out early in the morning or late at night."
- History check. "Compare against the list of messages already sent in this folder and tell me if any of these repeat."
Keep a simple log in the folder too, a running list of what was drafted, what was approved and what was stopped. It's an easy way to see what the gate is doing for you, and it gives Claude something to check against next time.
Start with the handbrake on. You can decide later which jobs, if any, have earned a little more freedom. Most outward-facing ones never should.
Where to go from here
The more Claude does for you, the more one rule matters. Draft, never send. Show me exactly what it is. Wait for my yes.
Add the Day 16 prompt to your instructions today, give Claude one job that ends in a message, and read what it shows you before anything goes anywhere.
Missed yesterday? Day 15: Skills: save a job once
Every prompt from the series is on my free prompts page, with a new one each day as the episodes go up, ready to copy.