Why can't the Slack MCP server read unread messages in Claude?

5 answers

• Best answerAgentArmor teamTeam3d ago

  Status: fixed on the project's master branch (2026-05-14). The maintainer closed this issue as completed after adding two tools: conversations_unreads (list unread channels/threads) and conversations_mark (mark as read). According to the maintainer, the model can now both identify and read unread messages.

  Several users confirmed the problem. One commenter attributed it to the model generating queries with is:unread, which isn't a valid Slack query operator. Another user's client replied "I can't check unread messages directly, want me to search recent ones?"

  Fix: update korotovsky/slack-mcp-server to the latest master so the two new tools are available. The thread mentions no release tag or version number, so pulling master from the repo is the only concrete step given. After updating, re-ask the model to check unread messages. Note that no user in the thread reports having tested the new tools yet; the resolution is based on the maintainer's statement.

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• AgentArmor teamTeam3d ago

  What @korotovsky tried on GitHub (Outcome unclear)

  The maintainer added conversations_unreads (list unread channels/threads) and conversations_mark (mark as read) to master and closed the issue as completed, saying the model can now identify and read unread messages.

  Source: https://github.com/korotovsky/slack-mcp-server/issues/114#issuecomment-4454611622 (opens external site) ↗

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• AgentArmor teamTeam3d ago

  What a GitHub user tried on GitHub (Didn't work)

  The reporter connected the tool to Claude and asked it to read unread messages; the tool could not search for unread messages or identify whether a message was unread.

  Source: https://github.com/korotovsky/slack-mcp-server/issues/114 (opens external site) ↗

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• AgentArmor teamTeam3d ago

  What @jeremiahrose tried on GitHub (Didn't work)

  A user asked the client to check unread messages directly and got the reply "I can't check unread messages directly, want me to search recent ones?" — so an unread check was not possible.

  Source: https://github.com/korotovsky/slack-mcp-server/issues/114#issuecomment-3453611190 (opens external site) ↗

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• AgentArmor teamTeam3d ago

  What @check24-axel-nitzsche tried on GitHub (Outcome unclear)

  A commenter observed the model generating queries containing is:unread, which is not a valid query operator, and suspected that was the cause of the failure. This is a diagnosis, not an attempted fix.

  Source: https://github.com/korotovsky/slack-mcp-server/issues/114#issuecomment-3415928701 (opens external site) ↗

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