Connect your own tools: custom API tools and MCP servers
Your agent can look things up or take actions in your own systems during a call, either by calling your API (Custom Tools) or by using the tools on an MCP server (MCP Servers). Both are under Integrations in the sidebar and need a plan that includes them.
Updated Oct 20, 2026 · 4 min read
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Custom Tools: call your own API #
- Open Integrations, then Custom Tools, and create a tool.
- Give it a clear name and description. The agent reads the description to decide when to use the tool, so say exactly what it does and when.
- Enter the method and the address (it must start with
https://). Under Inputs the agent collects from the caller, add each thing the agent should ask for, such as an order number. Headers, a request body, the reply format and the time limit are under Advanced, and most tools never need them. - Choose how to sign in to your API: none, a bearer token, a custom header, basic sign in, or OAuth client credentials.
- Pick which agent can use it, or leave it blank to give it to all your agents.
Every custom tool can also use {{caller_phone_verified}} in its address, headers or body. It is true only when the caller's number came from the phone network (a call or a text message). A name, email or phone number someone types into website chat or the Chat API is unverified, so check it on your side before acting on it.
If your API rejects an expired OAuth token, NovaReps gets a new token and tries once more on its own. If you change the OAuth details, the old token is dropped straight away.
MCP Servers: connect an MCP server #
- Open Integrations, then MCP Servers, choose Add MCP server, and enter its name and
https://address. - Choose how to sign in under Authentication:
- None for a public server.
- Bearer Token or Custom Header if the server gave you a key.
- Sign in with OAuth for hosted servers that ask you to log in. Save, then choose Connect in the server list and approve access on the server's own page.
- Use Manage Agent Access to pick which tools each agent can use. Only turn on the tools an agent needs: a long list makes the AI worse at picking the right one.
Why is a tool marked under "Tool changes"? #
The server changed what one of its tools says or does after you turned it on. Until you check it, NovaReps stops offering that tool to your agents, so a server can never change an approved tool without you knowing. Choose Approve tool changes to review the new version and turn it back on.
Why does a server say "Needs reconnect"? #
The server stopped accepting our sign in, for example because access was removed or expired. Its tools are paused. Choose Reconnect in the server list to sign in again.
Why does a tool say "needs credentials"? #
When you duplicate an agent, its custom tools are copied with it, but their saved logins (tokens, passwords, keys) are not. Each copied tool starts switched off. Click needs credentials in the tool list to open the tool, add the login, then turn the tool on. Until then the agent cannot use it. MCP servers are copied with the agent when your plan includes them.
What happens when a tool is slow or failing? #
- A tool call that takes too long is stopped, and the agent tells the caller it could not complete the request.
- Only a few tool calls per account run at the same time. If more are asked for at once, the agent hears that the service is busy and can try again.
- After 5 failures in a row, the tool or server is paused for 15 minutes and you get a notification. It resumes on its own after that.
Keep callers safe #
Anything a tool sends back is treated as information, never as instructions for the agent. Still, only connect servers and APIs you trust, and only turn on the tools each agent needs.