Slack MCP channels_list returns only 6 channels despite token having 15+ channel access
Using
slack-mcp-server@latestvia npx with stdio transport and a Slack user OAuth token (xoxp-...),channels_listreturns only 6 channels even though the user is in 15+ channels andconversations_search_messagesfinds messages in all of them. I triedchannel_types=public_channel,private_channel,im,mpimwithlimit=999. Is there a known fix or workaround for this? The token has scopes likechannels:read,channels:history,groups:read, andgroups:history.Originally asked on GitHub: https://github.com/korotovsky/slack-mcp-server/issues/148
6 answers
The issue is closed as completed, but no upstream release was named as the fix in the thread; the confirmed workaround is pinning
slack-mcp-serverto version1.1.26— one reporter downgraded and the tool then returned the expected channels. The maintainer could not reproduce the bug and added integration tests (commit5637b6f72f14459d896e0dc80cd69f1c7b10c82b) coveringprivate_channelcalls; he suggested re-checking the app manifest scopes fromdocs/01-authentication-setup.md. As general advice, if you usenpx, pin the version in your MCP config withnpx slack-mcp-server@1.1.26until the regression in newer builds is identified. Note that the user token in this report is axoxp-...token withadminandsearch:readscopes, so keep it out of logs and only run this MCP server in a trusted environment.Did this work for you?What @buildgreatthings tried on GitHub (Worked)
Downgraded the package from latest to 1.1.26; the reporter confirmed this restored the expected channel list.
Did this work for you?What a GitHub user tried on GitHub (Didn't work)
Called channels_list with channel_types=public_channel,private_channel,im,mpim and limit=999; only 6 of 15+ channels were returned even though conversations_search_messages proved the token could see more.
Source: https://github.com/korotovsky/slack-mcp-server/issues/148 (opens external site)
Did this work for you?What @buildgreatthings tried on GitHub (Didn't work)
Sent a tools/call request with arguments channel_types=private_channel and limit=100 using an xoxp token; public channels and DMs appeared but private channels were still missing.
Did this work for you?What @buildgreatthings tried on GitHub (Outcome unclear)
Inspected the JSON cache file and found public channels, DMs, and bot DMs but no private channels, matching the incomplete API response.
Did this work for you?What @korotovsky tried on GitHub (Outcome unclear)
Maintainer ran new integration tests and reproduced a private channel successfully in MCP Inspector, but this did not resolve the reporter's setup.
Did this work for you?
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