Slack plugin: MCP server returns error ('There's been a glitch...')

[syyunn]

Description

The Slack plugin (slack@claude-plugins-official) fails to connect because Slack's MCP server is returning an error.

Steps to Reproduce

1. Install the Slack plugin: /plugin install slack@claude-plugins-official
2. Restart Claude Code
3. Attempt to use Slack integration

Expected Behavior

The plugin should connect to Slack's MCP server and provide Slack search/messaging capabilities.

Actual Behavior

The MCP server at https://mcp.slack.com/sse returns Slack's generic error page:

"There's been a glitch... We're not quite sure what went wrong."

Technical Details

• Plugin config (.mcp.json):

{
  "slack": {
    "type": "sse",
    "url": "https://mcp.slack.com/sse"
  }
}

• The plugin distribution and configuration from Anthropic's side appears correct
• The issue is that Slack's hosted MCP server endpoint is not functioning

Environment

• Claude Code version: latest
• OS: macOS
• Date observed: 2025-12-28

Suggestion

This may need to be escalated to Slack, as they host the MCP server at mcp.slack.com. Alternatively, consider adding a note to the plugin description that Slack's MCP integration may have limited availability.