Build Custom Agent Tools with an API That Renders Natively on WhatsApp, Voice, Teams, and Web

Building a custom tool for an AI agent is rarely the hard part — deciding what the tool does and calling the right internal API is usually a day of work. What eats the rest of the week is everything downstream of that: if the tool asks the user to pick from three options, or fill in a date and an amount, that has to become a WhatsApp button menu on one channel, a spoken prompt on a phone call, an Adaptive Card in Teams, and a web component in a browser — four separate rendering paths for one piece of tool logic. Linkworld's Open SDK is built on the same channel-agnostic Response IR the platform's own agents use, so a tool you write once renders correctly on all four without you writing any of that per-channel code.

One Tool Call, Four Native Renderers — Not Four Things to Build

When a tool you write needs to offer the user a choice or collect structured input, it doesn't return raw text and leave formatting to guesswork, and it doesn't require you to hand-code a WhatsApp interactive message separately from a web modal. It returns a unified, channel-agnostic response shape, and the platform's per-channel renderers turn that same shape into a WhatsApp button menu, TTS-chunked speech on a voice call, an Adaptive Card in Teams, or native web UI — whichever channel the user is actually on. That's sustained integration work most agent-tooling APIs leave entirely to the builder, one channel at a time, because building and maintaining four renderers ad hoc is exactly the kind of infrastructure work most teams building an agent side-project don't have the time for. On Linkworld, it's already built into the layer your tool runs on.

Your Tool Runs Inside Companies That Were Already Onboarded, Not Empty Shells

A tool is only useful once someone with a real business is running it. Linkworld's automated onboarding pipeline is what seeds those businesses in the first place: when a company signs up, the pipeline fingerprints its existing site, classifies its business model, and seeds a full operating loop around it — marketing, sales, and finance departments already coordinating, an approval frame already in place. A custom tool built with the Open SDK plugs into that same operating loop as an app the company's operator can deploy — you're not building for a blank workspace, you're extending a company that's already mid-operation.

Sell What You Build Through the Marketplace, Priced Your Way

Once a tool is packaged as an app — manifest, workflows, tools, and channels bundled together — you can list it on the Linkworld marketplace instead of keeping it internal to one company. You choose the pricing model — free, one-time, subscription, or usage-based — in the dev console, and the platform's checkout and billing run underneath it; you're not integrating a payments provider or building a storefront to sell what you built.

Who This Is For

Developers building custom tools for an AI agent who don't want to own four separate channel-rendering implementations for every piece of tool output. If your tool needs to ask a question, present options, or collect structured input, and you want that to work correctly whether the user is on WhatsApp, a phone call, Teams, or the web — without writing that per-channel — this is the layer to build on. Same applies whether the tool stays inside your own company's operator or gets listed for other companies to buy.

Frequently Asked Questions

How do I build a custom agent tool with an API on Linkworld?

Install the Open SDK (pip install linkworld), scaffold a project with linkworld init, and write your tool's logic against it — there's no access gate or approval form to get started. Deploy with linkworld deploy.

Do I have to build separate UI for WhatsApp, voice, Teams, and web myself?

No. A tool's response goes through Linkworld's channel-agnostic Response IR — a single response shape that the platform renders natively per channel: WhatsApp button menus, TTS-chunked speech for voice calls, Adaptive Cards in Teams, and native components on web. You write the tool logic once.

Does my custom tool only work for one company, or can other companies use it?

Both. You can build a tool as an app for your own company's operator, or package it and list it on the Linkworld marketplace for other companies to install — companies that were themselves seeded through the platform's automated onboarding pipeline, so they're already running an operating loop, not a blank account.

How does pricing and billing work if I sell my tool on the marketplace?

You pick the pricing model in the dev console — free, one-time, subscription, or usage-based — and the marketplace handles checkout and billing for buyers. You don't build or integrate your own payments flow.