Connectors and Tools
Connectors are the apps and MCP servers your agent uses, such as Gmail, Notion or GitHub. Each one brings a set of tools: "search emails", "create a page", "open a pull request". You decide which tools are switched on and how each one runs.
Willow's gateway holds every sign-in and makes every call, so the agent never sees your password or API key.
Open the agent and click the Connectors tab.
Add a connector
- Click Add.
- Search for an app, or filter by category. Each tile shows the best way to connect it:
- Willow: hosted by Willow.
- Official: run by the app's own company.
- Community: built by someone else.
- Custom: an MCP server you added yourself.
- Click the app. Sprout adds it and switches on the tools that fit what your agent does.
- Click Connect on its card and sign in.
An agent can have up to 10 connectors.
Add your own MCP server
If the app you need isn't listed, paste its MCP URL into the search box, or click the Custom MCP tile.
- Under Remote (URL), enter the MCP URL. This is the server's Streamable HTTP endpoint and usually ends in
/mcp. - Optionally give it a Name. Without one, Sprout names it after the website.
- Click Add server. Sprout checks the server and adds it.
- If the server needs a sign-in, click Connect on its card.
Local MCP servers, which run a command on your own machine (Local (stdio)), are a premium feature. Click See Premium to contact us about turning them on. Remote servers by URL work on every plan.
Sign in to a connector
Until you sign in, the agent can't use the connector's tools, and the Connectors tab shows a dot. Click Connect on the card, or on the Overview tab under Sign in to its tools.
Every call runs as you, with your account. To change how you sign in, click the sign-in chip on the card ("Runs as you · OAuth" or "Runs as you · API key"):
- Connect my account · OAuth: sign in on the app's own page. This is the recommended choice when the app offers it.
- Connect my account · API key: paste a key from the app's settings.
Switching method signs you out of that app, so you connect again the new way. Servers that need no sign-in don't show the chip.
Choose its tools
Click a card to see its tools. Each tool has:
- A switch to turn it on or off. Only switch on what the agent needs.
- A risk level from Willow:
| Risk | What it means |
|---|---|
| Low risk | It looks things up or makes small changes that are easy to undo. |
| Medium risk | It changes your data, like creating or editing items. Mistakes can be fixed by hand. |
| High risk | It does things that are hard to take back, like deleting data or sending messages for you. |
| Critical | It can cause lasting damage, like wiping data, changing access or moving money. |
- read-only when it never changes anything.
- How it runs (see below).
If a connector hasn't listed its tools yet, they appear once you connect it.
How each tool runs
| Setting | What happens |
|---|---|
| Use freely | The tool runs whenever the agent needs it, without asking. |
| Ask Each Time | Every call waits for you to approve it before it runs. |
| Require Session | Instinct and Grok Bot only: the tool runs only in a session you approved. See Access bundles. |
By default, every tool that changes data asks each time and read-only tools run freely.
On Willow Agents, you approve calls right in the chat. Slack can't show an approval, so tools that ask each time are blocked there. See Approve tool calls.
Add rules
Rules let you block a call you never want, or ask first only when it matters, based on what the agent sends. For example, "block send_email when to ends with @rival.com", or "ask first when amount is more than 100".
Click Rules on a card. See Tool rules.
Built-in tools
Agents on Willow Agents also have tools that need no connector. They are listed under Built-in tools on the same tab. See Built-in tools.
Remove a connector
Click the remove icon on its card. The agent stops using it straight away.