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How Do You Build a Custom Tool with Macha's AI Tool Builder?
Macha's AI Tool Builder turns any app with an API into a tool your agents can use: you paste an API key, describe the tool, and it builds and tests it. It covers apps Macha has no connector for, including your own internal systems.
Key takeaways
- Macha's AI Tool Builder builds a custom tool from an API key and a plain description, then works out the endpoint and request and tests the connection.
- In the demo, Macha's AI Tool Builder builds a Postmark tool for sending email from the instruction "create a Postmark connector that can send emails."
- Custom tools can also be built by hand in Macha's Create Custom Tool form, which sets the Label, Description, Method/URL, Read vs. Write, Authentication and Headers.
- Macha includes the AI Tool Builder and custom API tools on every plan, which starts at $299 a month for 750 tickets.
- Manual setup beats the AI Tool Builder when a tool needs an unusual auth scheme, a specific response mapping or a tightly templated request body.
To build a custom tool with Macha's AI Tool Builder, open Custom Tools, click Build with AI, paste the API key for the app, and describe the tool you want (for example, "create a Postmark connector that can send emails"); the builder works out the endpoint and request, assembles the tool and tests it. Custom API tools are included on every Macha plan, from $299 a month for 750 tickets.
What does the AI Tool Builder look like in action?
What are the 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.
The AI Tool Builder is the faster route because it handles the fiddly part: endpoints, auth headers and request shape.
How does the AI Tool Builder build a tool?
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 the AI Tool Builder 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 should you build a custom tool 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.
Which Macha plans include the AI Tool Builder?
The AI Tool Builder is available on every plan, as is every other feature. Macha has one plan priced by ticket volume, from $299 a month for 750 tickets, and custom API tools are included at every tier. See pricing for the full ladder.
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? All of them. Every feature is on every tier, and the free trial gives $50 of usage (about 125 tickets) with no credit card and no time limit.
What's the short version?
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, with 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. $50 of free usage, no credit card required, no time limit. Start free.
