MCP servers

What you will achieve

An agent will be able to use the tools of an MCP (Model Context Protocol) server: look things up, create records, send messages, whatever the server offers. You connect the server once, tick the tools you want, and give them to any agent like any other tool.

Prerequisites

• An MCP server that is reachable on the internet over https, and its address (it usually ends in /mcp). The service you want to use shows it in its developer or MCP settings.
• The key the server asks for, if any: an access token or an API key. Servers that sign you in through a browser window (OAuth) cannot be connected yet.
• You must be an owner or admin. Members can look at servers and test their tools, but not change them.

Step-by-step setup

1. Open Tools, then the MCP servers tab.
2. Choose Connect server.
3. Paste the Server address.
4. Choose How does it sign you in?: Access token (Authorization: Bearer) for most servers, Key in a header I choose if the service names a header (then enter the Header name, such as X-API-Key), or No key.
5. Enter the Access token or Key. Give the server a Name if you want one of your own.
6. Choose Connect. Phynxa connects, asks the server what it offers and saves it. If it cannot connect, the dialog says why and nothing is saved.

Choose the tools

Under the server, choose Show tools. Each tool shows what it does and what the agent will fill in (a question mark means optional). Tick the ones you want and choose Add tool. They now appear on Tools, API tools, like any other tool, and you can rename them or change their description and timeout.

A tool marked Can't be used by an agent needs something an agent cannot give it, and the reason is shown.

Give the tools to an agent

Open the agent, Tools tab, Add tool, then choose MCP. Pick the server, tick its tools and choose Add tool, then Save the agent. For a WhatsApp agent, do the same on its Tools tab (see Create a WhatsApp agent).

On a call the agent waits for the answer unless you switch on Run in the background on the tool's page. On WhatsApp it always waits.

Note. A WhatsApp agent answers every customer, so give it only tools you are happy for any customer to cause.

Manage a server

• The switch turns a server off and on. While it is off its tools do not run, and the agent is told so.
• Reconnect connects again and lists the tools again. Use it after the service adds or changes tools. Tools you already added get the new inputs; the names and descriptions you wrote stay.
• Edit changes the name, address or key. A key you leave empty is kept.
• Remove deletes the server and every tool made from it. Agents using them lose them.

A red banner on the server shows the last problem and a Reconnect button. The status also changes by itself: a tool call that fails because the server is down marks it, and the next call that works clears it.

What to know

• Your key is private. It is stored encrypted, sent only to the server it belongs to, and never shown again, not even to you. Some services put the key in the address itself (?key=...): that is kept encrypted too, and the page shows the address without it.
• The server is a third party. Its descriptions and answers are treated as information for the agent, never as instructions, and the agent is told to read details back before doing anything that cannot be undone.
• Public servers only. An address that points at a private network is refused.
• Limits. Up to 20 servers per workspace. An answer is cut at about 6,000 characters, and images and audio in an answer are not passed to the agent. A tool that asks for an object or a list receives it as JSON text, which the agent writes for you. A tool that stops to ask the user a question cannot be used by an agent.
• Repeats. If an agent asks for the same change twice in one call, it is made once. Tools the server marks as read-only are not held back.

Testing

Open the tool (Tools, then its name), fill in the inputs under Test and run it. It calls the server for real, exactly as the agent would, and shows the answer and how long it took. Then try the agent's Chat test.

Expected result

The server shows Connected with its tools listed, the tool's Test returns the server's answer, and the agent uses the tool in a chat or on a call.

Troubleshooting

Related guides

• Tools overview
• Connected-app tools
• Test and troubleshoot tools