Slack

The Slack auth provider enables tools and agents to call Slack APIs  on behalf of a user.

What’s documented here

This page describes how to use and configure Slack auth with Arcade.

This auth provider is used by:

• The Arcade Slack MCP Server, which provides pre-built tools for interacting with Slack
• Your app code that needs to call the Slack API
• Or, your custom tools that need to call the Slack API

Configuring Slack auth

In a production environment, you will most likely want to use your own Slack app credentials. This way, your users will see your application’s name requesting permission.

Before showing how to configure your Slack app credentials, let’s go through the steps to create a Slack app.

Create a Slack app

• Follow Slack’s guide to registering a Slack app 
• If you plan to use the Arcade Slack MCP Server, select the scopes below (include additional scopes for your application’s authorization needs or custom tools, in any):
  • channels:history
  • channels:read
  • chat:write
  • groups:read
  • groups:history
  • groups:write
  • im:history
  • im:read
  • im:write
  • mpim:history
  • mpim:read
  • mpim:write
  • users:read
  • users:read.email
• Set the redirect URL to the redirect URL generated by Arcade (see below)
• Copy the client ID and client secret

Next, add the Slack app to Arcade.

Configuring your own Slack Auth Provider in Arcade

Using Slack auth in app code

Use the Slack auth provider in your own agents and AI apps to get a user token for the Slack API. See authorizing agents with Arcade to understand how this works.

Use client.auth.start() to get a user token for the Slack API:

from arcadepy import Arcade
 
client = Arcade()  # Automatically finds the `ARCADE_API_KEY` env variable
 
user_id = "{arcade_user_id}"
 
# Start the authorization process
auth_response = client.auth.start(
    user_id=user_id,
    provider="slack",
    scopes=[
        "chat:write",
        "im:write",
        "users.profile:read",
        "users:read",
    ],
)
 
if auth_response.status != "completed":
    print("Please complete the authorization challenge in your browser:")
    print(auth_response.url)
 
# Wait for the authorization to complete
auth_response = client.auth.wait_for_completion(auth_response)
 
token = auth_response.context.token
# Do something interesting with the token...

import { Arcade } from "@arcadeai/arcadejs";
 
const client = new Arcade(); // Automatically finds the `ARCADE_API_KEY` env variable
 
const userId = "{arcade_user_id}";
 
// Start the authorization process
let authResponse = await client.auth.start(userId, "slack", {
  scopes: ["chat:write", "im:write", "users.profile:read", "users:read"],
});
 
if (authResponse.status !== "completed") {
  console.log("Please complete the authorization challenge in your browser:");
  console.log(authResponse.url);
}
 
// Wait for the authorization to complete
authResponse = await client.auth.waitForCompletion(authResponse);
 
const token = authResponse.context.token;
// Do something interesting with the token...

Using Slack auth in custom tools

You can use the pre-built Arcade Slack MCP Server to quickly build agents and AI apps that interact with Slack.

If the pre-built tools in the Slack MCP Server don’t meet your needs, you can author your own custom tools that interact with the Slack API.

Use the Slack() auth class to specify that a tool requires authorization with Slack. The context.authorization.token field will be automatically populated with the user’s Slack token:

from typing import Annotated
 
from slack_sdk import WebClient
 
from arcade_tdk import ToolContext, tool
from arcade_tdk.auth import Slack
from arcade_tdk.errors import RetryableToolError
 
 
@tool(
    requires_auth=Slack(
        scopes=[
            "chat:write",
            "im:write",
            "users.profile:read",
            "users:read",
        ],
    )
)
def send_dm_to_user(
    context: ToolContext,
    user_name: Annotated[
        str,
        "The Slack username of the person you want to message. Slack usernames are ALWAYS lowercase.",
    ],
    message: Annotated[str, "The message you want to send"],
):
    """Send a direct message to a user in Slack."""
 
    slackClient = WebClient(token=context.authorization.token)
 
    # Retrieve the user's Slack ID based on their username
    userListResponse = slackClient.users_list()
    user_id = None
    for user in userListResponse["members"]:
        if user["name"].lower() == user_name.lower():
            user_id = user["id"]
            break
 
    if not user_id:
        raise RetryableToolError(
            "User not found",
            developer_message=f"User with username '{user_name}' not found.",
        )
 
    # Step 2: Retrieve the DM channel ID with the user
    im_response = slackClient.conversations_open(users=[user_id])
    dm_channel_id = im_response["channel"]["id"]
 
    # Step 3: Send the message as if it's from you (because we're using a user token)
    slackClient.chat_postMessage(channel=dm_channel_id, text=message)