Which way should I choose, the API or Slack’s MCP server?

The API way is recommended: its tools are Flowplane’s, they are the same for everyone, they work with any workspace and they return only what is needed (author, time, text, replies). Slack’s MCP server gives you Slack’s own tools, whatever Slack lists, but Slack only lets apps listed in the Slack Marketplace use it, and a workspace administrator may have to approve Flowplane.

What can the assistant change in Slack?

With the API way, two things: post a message in a channel or thread and add an emoji reaction, both in your name and both after your approval. Everything else only reads. Through Slack’s MCP server, reads are allowed and changes ask first; Flowplane asks Slack only for reading, searching, posting and reacting, so canvases, lists and files are left out.

Can the assistant read every channel?

No. It acts as the person who signed in, so it sees the channels and messages that person can see, and nothing more.

Does Claude Code see the password or key for Slack?

No. You sign in to Slack through Flowplane, which keeps that sign-in sealed. Claude Code only gets a Flowplane sign-in for you, which you can revoke in the console.

Can Claude Code change things in Slack without asking?

Not by default: every change in Slack waits for your approval in the browser. Your workspace’s rules decide, per tool.

Connect Claude Code to Slack

Claude Code reaches Slack through one Flowplane address. You add Slack once in Flowplane, add that address to Claude Code, and sign in. Search Slack, read channels and threads and look people up with your AI assistant. Messages and reactions are posted in your name, after you approve.

Connect Slack →Set up your assistant

Tools: 6 read · 2 change
Sign-in: Own account or shared key
Approval, by default: Changes wait for you
MCP server: Flowplane’s tools

1
Add Slack in Flowplane
In the Flowplane console, add Slack, choose a way in (API, recommended, or Slack’s MCP server) and sign in with Slack.
Each person signs in with their own Slack account, so an assistant sees only the channels that person is in and posts in their name. A workspace administrator may have to approve Flowplane in Slack first. For a shared connection you can also paste a token instead: a user token (xoxp-) or a bot token (xoxb-), which then posts as that bot. Flowplane keeps it sealed; the assistant never sees it.
Connect Slack →
2
Add Flowplane to Claude Code
Your address is shown in the Flowplane console; it looks like
https://mcp.flowplane.eu/<your-label>
1. Add the server in a terminal with the command below.
2. Start Claude Code and run /mcp, choose flowplane and sign in to Flowplane in the browser (or run claude mcp login flowplane).
3. Ask your question; Claude Code calls the tools it needs.
```
claude mcp add --transport http flowplane https://mcp.flowplane.eu/<your-label>
```
Steps checked against the vendor’s documentation (Anthropic)
3
Ask Claude Code
- “What did people say in #support yesterday?”
- “Find the messages from Sarah about the Q4 budget.”
- “Summarise the thread about the release that started this morning in #engineering.”
- “Who is Tom Peeters and what time is it where he is?”
- “Reply in that thread that the fix is live, and add a thumbs-up to the bug report.”

What it can do

What Claude Code can do in Slack

Slack is where many teams talk. Through Flowplane an AI assistant can search the messages you can see, read a channel or a whole thread, list channels and people and look someone up. It can post a message or add a reaction in your name, and each of those waits for your approval first.

Reads6

List channelsThe channels in your workspacelist_channels
List peopleThe people in your workspacelist_users
Look up a personTheir name, job title and time zoneget_user
Read a channelThe latest messages in a channelread_channel
Read a threadA message and all its repliesread_thread
Search messagesFind messages by words or sendersearch_messages

Changesasks first2

Post a messagePosts in a channel or thread, as youpost_message
Add a reactionAdds an emoji reaction, as youadd_reaction

FAQ

Questions

Which way should I choose, the API or Slack’s MCP server?: The API way is recommended: its tools are Flowplane’s, they are the same for everyone, they work with any workspace and they return only what is needed (author, time, text, replies). Slack’s MCP server gives you Slack’s own tools, whatever Slack lists, but Slack only lets apps listed in the Slack Marketplace use it, and a workspace administrator may have to approve Flowplane.
What can the assistant change in Slack?: With the API way, two things: post a message in a channel or thread and add an emoji reaction, both in your name and both after your approval. Everything else only reads. Through Slack’s MCP server, reads are allowed and changes ask first; Flowplane asks Slack only for reading, searching, posting and reacting, so canvases, lists and files are left out.
Can the assistant read every channel?: No. It acts as the person who signed in, so it sees the channels and messages that person can see, and nothing more.
Does Claude Code see the password or key for Slack?: No. You sign in to Slack through Flowplane, which keeps that sign-in sealed. Claude Code only gets a Flowplane sign-in for you, which you can revoke in the console.
Can Claude Code change things in Slack without asking?: Not by default: every change in Slack waits for your approval in the browser. Your workspace’s rules decide, per tool.

Your assistant

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Add Slack in Flowplane

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