How to Build Custom Tools with the AI Tool Builder on Macha
Macha has connectors for the apps most teams use — but not for every app, and definitely not for your homegrown internal systems. The good news: as long as something has an API endpoint, you can turn it into a tool your agents use. And the fastest way to do that isn't to wire it up by hand — it's to let the AI Tool Builder do it for you.
Watch it build a tool
Two ways to create a custom tool
From the Custom Tools menu in the left nav, you can build a tool two ways:
- Manually — configure the method, URL, auth, and response mapping yourself (full control; see how to connect a custom tool).
- With the AI Tool Builder — describe what you want and let the AI assemble it.
This guide is about the second one, because it's the one that saves you the fiddly part.
How the AI Tool Builder works
The flow is genuinely conversational:
- Click the AI Tool Builder (Build with AI) on the Custom Tools page.
- Give it your API key for the app you're connecting.
- Tell it which app and what tools you want. In the demo, that's Postmark for sending email — "create a Postmark connector that can send emails."
- Let it build. The AI Tool Builder takes your key and your description, figures out the endpoint and request shape, and assembles the tools — testing the connection so you know it works before you rely on it.
Instead of looking up Postmark's API docs, getting the auth header exactly right, and mapping the response by hand, you describe the outcome and the builder handles the mechanics.
Why use it instead of building by hand
- It skips the error-prone parts. Auth headers, request bodies, and response mappings are exactly where manual setups go wrong. The builder captures a working configuration from a real test.
- You don't need the API memorized. Describe the capability you want; the builder works out the details.
- It's fast. A new tool — and a new agent capability — in a couple of minutes.
Once the tool is built, it's a normal custom tool: an org-level resource you can add to any agent via its Tools toggle.
When to build manually instead
The AI Tool Builder covers most cases, but build by hand when you need precise control — an unusual auth scheme, a specific response mapping, or a tightly templated request body. You get the same result either way; it's just a question of whether describing or configuring is faster for that endpoint.
Plan availability
The AI Tool Builder is available on Professional and Enterprise plans.
Frequently asked questions
What is the AI Tool Builder? A feature that turns an API into a custom tool by chat — you give it your API key and describe the tool, and it builds and tests it.
What do I need to use it? An API key for the app and a description of the tool(s) you want.
Is it different from building a custom tool manually? Same result — the AI Tool Builder just assembles the configuration for you instead of you doing it by hand.
Can any agent use the tool afterward? Yes — it's an org-level custom tool; add it to any agent via the Tools toggle.
Which plans include it? Professional and Enterprise.
The bottom line
The AI Tool Builder is the shortcut from "we use an app Macha doesn't have a connector for" to "my agents can use it." Give it your API key, describe the tool, and it builds and tests the connection — no API-doc spelunking required. Build manually when you need fine control; otherwise, just describe it.
Give your agents a new power: build a custom tool by chat in minutes. 7-day free trial, no credit card required. Start free.
