Connecting a Slack workspace

Slack gives this package something Gmail cannot: read and write scopes that are genuinely disjoint. A token holding only *:history and *:read cannot call chat.postMessage at all, and Slack's own consent screen says so. That is why there are two install modes and why the default is the narrow one.

Be precise about what the narrow mode promises. It is "this package cannot post", not "nothing on this machine can post". A second Slack MCP server holding a write token for the same workspace lets an agent post without going near this one, and the Gmail release found exactly that shape on the author's own machine. Check the client's MCP server list for other Slack servers, and never state the promise more broadly than the sentence above.

The two modes