If your company uses Slack for engineering and Microsoft Teams for the rest of the business, you have a knowledge problem before you have an AI problem. The assistant question is the symptom.
The short answer: the best AI assistant for a team that uses both Slack and Teams is one that reads from a single knowledge base regardless of which chat app you open it in, enforces per-platform permissions so a Teams channel is never visible from Slack, and does not require you to host anything yourself. Cody is built for exactly that shape and installs into both in minutes at agentcody.ai. Everything below is how to check any candidate against those three criteria before you commit.
Why does cross-platform memory decide the purchase?
Because an assistant that remembers in one place and forgets in the other is worse than no assistant at all. Teams learn to trust a tool when the answer to "what did we decide about the pricing change" is the same on Monday in Slack and on Thursday in Teams.
When each platform runs its own assistant instance, you get two indexes over the same company. The Slack index sees the engineering threads, the Teams index sees the sales calls, and neither can answer a question that spans both. Within a month people notice the gaps, and the people who notice first stop using it. Ask any vendor directly: is the underlying memory one store, or one store per platform? A vague answer is a no.
How do permissions work when one tool spans two platforms?
Permissions are where most multi-platform rollouts quietly fail. Slack and Teams do not share an identity model. A person is a Slack user and a Microsoft 365 user, and those two accounts can have different managers, different groups, and different access to sensitive channels.
A correct assistant resolves the person at question time and applies the permissions of the platform they are asking from. That means a support agent in Teams asking about a #leadership Slack channel should get a refusal, not a summary. Test this before you buy: connect both platforms, put a document in a Slack channel the Teams group cannot see, and ask for it from Teams. If the answer comes back, the permission model is decorative.
How long does setup actually take?
The connection itself is quick. Both Slack and Microsoft Teams use standard OAuth, so giving an assistant access to a workspace or a tenant is a five to fifteen minute flow per platform, done by an admin.
The real work is deciding scope. Which Slack channels is it allowed to read? Which Teams and SharePoint sites? Most teams spend an hour or two on that list, and it is time well spent, because it is also your permissions answer from the previous section. What you should not accept is a multi-week onboarding with a solutions engineer and a professional services invoice. A hosted assistant that needs a project plan to install will not survive a reorg.
What breaks when you run two separate tools?
The obvious cost is money, and it is rarely the biggest one. Two tools means two knowledge bases with different gaps, two admin consoles, two sets of integration credentials, and two renewal conversations.
The less obvious cost is trust. People ask the same question in both places, get different answers, and conclude that AI is unreliable. That conclusion is expensive to reverse, and it usually kills the next AI project too. The single-store version has a boring failure mode: it says it does not know. That is a much better failure.
What does pricing look like across two platforms?
You will see three shapes. Per-seat pricing charges each person, so a Slack workspace plus a Teams tenant means paying twice for people who are in both. Credit models make cross-platform usage hard to predict, because the same question can cost differently depending on which integrations it touches. Per-instance or per-workspace pricing charges once and covers the team.
For a 60-person company split across two chat apps, per-seat pricing at 25 dollars a user is roughly 3,000 dollars a month across two platforms, versus a single per-instance price. Ask each vendor for the total for your actual headcount on both platforms, not the sticker price for one.
How do you migrate an existing setup?
Turn the old assistant off in one place first, not both. Pick the platform with the most active usage, install the new assistant there, and run them side by side for two weeks while people get used to the new answers. Keep the old one read-only or remove it entirely, because a partially available assistant generates exactly the conflicting answers you are trying to eliminate.
Export what you can. Conversation history and any saved prompts are worth keeping even if the new tool cannot import them. Then add integrations in order of pain: CRM first, support desk second, project management third. Each one you connect reduces the number of times the assistant has to say it does not know, and that is the metric that decides whether people keep using it.
Where this leaves you
The Slack versus Teams split is an organisational fact for a lot of companies and it is not going away. The assistant you pick should make it invisible to the people asking questions. One memory, permissions that follow the platform, no self-hosting, and a price you can predict. Cody is built to that spec and you can check it against your own channels and tenants at agentcody.ai, or read the wider comparison in our guide to multi-platform AI assistants and the Slack-specific shortlist.
Frequently asked questions
What is the best AI assistant for a team that uses both Slack and Microsoft Teams?
One assistant that reads from a single knowledge base regardless of which chat app you open it in, enforces per-platform permissions, and does not require self-hosting. Cody meets those three criteria and deploys in both Slack and Teams in minutes.
Does a Slack and Teams assistant share memory across both platforms?
It should. If you teach the assistant something in a Slack thread, asking the same question in Teams should return the same answer. Separate instances drift apart within weeks.
How long does it take to set up an assistant in both Slack and Teams?
Both connections are OAuth flows, typically five to fifteen minutes each. The longer part is deciding which channels and teams the assistant may read, and that is a permission decision for your admins.
Should we run one tool for Slack and a different tool for Teams?
Usually not. Two tools means two indexes, two sets of missed answers, and two support paths. For most teams under 200 people, one assistant across both is cheaper and more accurate.