Custom Tools Explained: How to Connect Your Own Systems to Kai With Tool Library

Tool Library is where you connect an outside system — a scheduling tool, a custom internal API, another piece of software your business already runs on — so Kai can use it on a live call. Every KaiCalls agent ships with a fixed set of built-in actions (texting, sending saved links, checking a connected calendar). Tool Library is what you use when the business runs on something built-in tools don't cover.

This guide explains what a custom tool actually is, what Kai is and isn't allowed to do with one, how the approval system keeps you in control, and how to connect one.

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Table of Contents

1. What a custom tool is
2. Built-in tools vs. custom tools
3. How the risk and approval system works
4. Connecting a provider, step by step
5. What happens when a tool changes underneath you
6. What it costs
7. FAQ

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What a custom tool is

Every custom tool in KaiCalls comes from an MCP provider — a server that exposes a list of actions your agent can call mid-conversation, the same way it can send a text or check a calendar today. You connect the provider once in Dashboard > AI & Automation > Tool Library, KaiCalls discovers what actions it offers, and you decide which of those actions Kai is allowed to actually use.

That's the whole shape of it: connect a provider, see its tools, turn on the ones you want live.

Built-in tools vs. custom tools

Built-in tools — texting callers, sending a saved link, checking availability, booking an appointment — live in the agent editor's Actions tab and work out of the box once the underlying connection (phone number, calendar) is set up. They cover what almost every business needs.

Custom tools are for everything else: a scheduling system that isn't Google Calendar, an internal lookup, a proprietary API, a niche piece of software specific to your industry. If it isn't one of KaiCalls' built-in actions, Tool Library is how it gets in front of Kai.

How the risk and approval system works

Every discovered tool gets a risk badge before you can turn it on, and the badge decides how much oversight it gets on a live call:

• Read — can run after normal policy checks. Looking something up carries no downside, so there's no extra gate.
• Low — Kai confirms out loud before running it. A caller hears the action described back before it happens.
• Medium or high — queues for your approval instead of running immediately. Kai tells the caller it's being taken care of, and the action waits in Pending Approvals until you approve or reject it.
• Blocked — can't be enabled at all until it's reviewed outside the normal flow. This is the fallback for anything KaiCalls can't yet classify safely.

That means a tool that only reads data can go live the same day you connect it, while a tool that writes something consequential — charges a card, cancels a booking, changes a customer record — never runs without a human saying yes first.

Connecting a provider, step by step

1. Open Dashboard > AI & Automation > Tool Library.
2. Click Add Sandbox to try the whole flow safely first, or Connect MCP to add a real provider.
3. Enter the provider name, the MCP server URL, the auth type, and a credential reference if the provider needs one.
4. Click Save and Discover — KaiCalls fetches the provider's tool catalog.
5. Review each tool's risk badge, then click Enable on the ones you want Kai to use.
6. Approve or reject anything that lands in Pending Approvals as it comes in.

What happens when a tool changes underneath you

Providers update their own tools — a field gets renamed, an action gets removed, a new one gets added. Tool Library tracks that under Need Review: anything new, changed, or removed since the last discovery shows up there instead of silently changing what Kai does mid-flight. You decide whether to re-approve the changed version or turn it off.

What it costs

Tool Library and custom tools are included on every KaiCalls plan — Solo starts at $69/mo, Pro at $199/mo, both with a generous answered-call allowance and no per-minute overage. Connecting a provider and enabling tools costs nothing extra beyond whatever the third-party provider itself charges for its own API.

FAQ

Do I need Tool Library if I just want Kai to text and book appointments? No. Those are built-in actions in the agent editor's Actions tab and don't require Tool Library at all. Tool Library is only for connecting something beyond the built-ins.

Can Kai take a risky action without me knowing? No. Anything flagged medium or high risk queues for your approval and waits — it does not run until you approve it.

What is a sandbox connection for? It lets you test the whole connect-discover-approve flow with safe, fake data before pointing Tool Library at a real system.

What happens if a connected provider goes down or changes its tools? KaiCalls surfaces connection health and flags any tool that's new, changed, or removed under Need Review, so you always know before Kai relies on something that's shifted.

Can more than one agent use the same connected provider? Yes — a connection lives at the business level, and you choose which of its tools are enabled per agent.

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See what your systems could plug into. Open Dashboard > AI & Automation > Tool Library and try a sandbox connection, or call the KaiCalls demo line at (417) 386-2898 to talk to Kai first, or visit kaicalls.com.