claude mcp add refused: managed settings, plugins only, Sume

If claude mcp add now refuses, your managed settings restrict MCP servers to plugins, and a server added by hand would never load. Since 2.1.284 Claude Code says so instead of saving it. The Sume server is one remote URL, https://mcp.sume.com/mcp, so an admin must allow it or ship it in a plugin.

Vendor behavior is from the Claude Code changelog; Sume's URL and transport are from the MCP quickstart, read 2026-10-01.

What does the refusal mean?

The 2.1.284 entry (September 28, 2026) says claude mcp add used to report success when managed settings restrict MCP servers to plugins. It now refuses and says what to do, instead of saving a server that never loads. The refusal is a policy result, not a Sume error.

What does the Sume server need to be allowed?

The quickstart command is claude mcp add --transport http sume https://mcp.sume.com/mcp. For other clients it says to point a streamable HTTP MCP server at the same URL. Give your admin these facts:

What are my options under a plugins-only policy?

Ask for the server to be packaged in an approved plugin, or for the managed settings to name the Sume URL. A related allowlist case is covered in managed MCP config and the Sume hosted server. I did not find a Claude Code setting in the changelog line itself, so check your admin documentation for the exact key.

How do I check it worked?

After the server is allowed, confirm it is connected in Claude Code's MCP status UI, then ask Claude to call tools_list or mcp_health, as the quickstart suggests.