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MCP servers
Give Piste your business's own tools by adding an MCP server on the Apps page. Piste judges each call, asks before risky ones and refuses them in automation runs.
An MCP server gives Piste your business's own tools, such as a stock feed or an internal system, over the Model Context Protocol. The workspace owner adds one on the Apps page (Apps, in the links at the foot of the sidebar) by its URL, and Piste can then use its tools in the owner's conversations and automations. Piste judges each call: reads run, and anything that could do harm waits for approval.
How do I add an MCP server?
Open the Apps page
Press Apps in the links at the foot of the sidebar and scroll to MCP servers, "Your own tools, over the Model Context Protocol."
Press Add server
Press Add server. The "Add an MCP server" dialog opens.
Enter a name and URL
Give the server a name, such as "Stock feed", and its URL, such as https://mcp.example.com/mcp.
Choose how it signs in
Under "Authentication", choose None, Bearer token or API key header. For a bearer token, paste it into "Token". For an API key header, enter the "Header name", such as X-Api-Key, and paste the "Key".
Press Add server
Press Add server. The server appears in the list with a switch, and Piste can use its tools from your next message.
The token or key is stored encrypted and never shown to Piste's agent.
What are the rules for the URL and name?
Piste checks the URL when you add the server, and checks the address again right before every connection.
| Rule | Detail |
|---|---|
| Protocol | http or https. With a token or key, https only. |
| Public address only | The host must resolve only to public internet addresses: never localhost, a private network or a link-local address. |
| Nothing extra in the URL | No user name or password, query string or fragment. |
| Name | Letters, numbers and spaces, plus ., _ and -, up to 60 characters. A name the same as, or very like, another server's is refused. |
| Header name | Letters, numbers and dashes, up to 64 characters. It can't be Authorization: choose Bearer token for that. |
When Piste refuses a URL, it says "That URL can't be used:" and why.
How does Piste decide when to ask?
Piste can't know what your server's tools do, so it judges each exact call from the tool's name and its input.
| The call | What happens in your conversation |
|---|---|
| Reads, searches and lookups | Runs without asking |
| A small, reversible change to the business's own records | Runs without asking |
| Deleting or overwriting data | Waits for approval |
| Moving money, refunds or discounts | Waits for approval |
| Messaging customers or anyone outside the business | Waits for approval |
| Publishing or changing anything a customer can see | Waits for approval |
| Changing access, credentials or settings | Waits for approval |
| Anything whose effect is unclear | Waits for approval |
This is a judgement of each call against these rules, not a fixed list of your server's tools, so the same tool can run freely with one input and ask with another.
Every decision about a call, and how each call that ran ended, is recorded in the decision log, reads included.
What can automations do with an MCP server?
An automation run gets the same servers, but nobody is there to approve. A call that would wait for approval is refused instead: "Not called: this could change something, and an automation run can't ask anyone to approve it."
A dry run from Try it now gets no MCP servers at all, since Piste can't tell a server's reads from its writes ahead of time.
Who can use MCP servers?
Only the workspace owner can add, switch off or remove a server. Only the owner's conversations and automations get the servers, so a teammate talking to Piste in Slack can't reach your business's systems through it. Piste can't add a server by itself.
How do I switch off or remove a server?
Each server in the list has a switch. Turn it off to stop Piste using the server without removing it. The change applies from your next message.
To remove a server, press the bin icon beside it, then Remove to confirm. Piste loses the server's tools and forgets its token or key.
Related
- Connected apps: Gmail, Notion and other apps, connected with a sign-in.
- Approvals: who can approve a call, and where.
- Decision log: every decision Piste's approval checks made.