claude mcp add succeeded but no server? Verify Sume with mcp_health

If claude mcp add said it worked but the server is missing, the config file may not have been written. Claude Code 2.1.283 (2026-09-25) fixed claude mcp add, add-json and remove reporting success in that case, for example inside a sandbox. Update, run claude mcp list, and then call mcp_health to prove the Sume server is really connected.

Changelog read 2026-10-01; commands from the MCP quickstart.

What is the documented Sume add command?

Two commands: claude mcp add --transport http sume https://mcp.sume.com/mcp, then claude mcp login sume. The quickstart says to confirm the server is connected in Claude Code's MCP status UI, then call tools_list or mcp_health.

How do I prove the add really saved?

Why might a sandbox lose the entry?

The changelog names a sandbox as an example of a config file that could not be written. The older behavior reported success anyway, so an entry could look added and then be absent in the next session. If mcp list still shows nothing on the fixed version, the add now fails loudly; check the error and the scope you added to. For policy-driven refusals, see add refused by managed settings.

What does mcp_health not tell me?

It confirms the connection, not that a tool will run. A default OAuth grant is read-only (mcp:read); write and paid tools return insufficient_scope until you grant mcp:write or use an API key.