Claude Code "No such tool available" on a resumed MCP session
After resuming a Claude Code session, a first MCP call could fail with No such tool available. Claude Code 2.1.284 waits up to 10 seconds. The Sume side.
If Claude Code answers "No such tool available" for an MCP tool right after you resume a session, the server was probably still connecting when the call fired. Claude Code 2.1.284 fixed that case: the call now waits up to 10 seconds for the server. If the error persists past that, or the Sume tool you want is simply not listed, the cause is on the connection or the session's scopes.
What did Claude Code change for resumed sessions?
The Claude Code changelog for version 2.1.284 says it fixed MCP tool calls in a resumed session failing with "No such tool available" while their server was still connecting, and that the call now waits up to 10 seconds for the server. The same release added /mcp reconnect all for servers that failed to connect. Nothing in that entry changes what a server exposes; it only changes how long the first call waits.
| Cause | Where it lives | What to do |
|---|---|---|
| Server still connecting on resume | Claude Code | Update to 2.1.284 or later, retry after a few seconds |
| Server never connected or needs sign-in | Connection state | Check Claude Code's MCP status UI, run the login again |
| Tool hidden by the session's scopes | Sume session | Grant Write on consent, or call tools_list to see what is visible |
Is the Sume server connected?
Sume's quickstart adds the server with claude mcp add --transport http sume https://mcp.sume.com/mcp and claude mcp login sume. It then says to confirm the server is connected in Claude Code's MCP status UI and to ask Claude to call tools_list or mcp_health. mcp_health confirms the endpoint, the auth source and the safety posture, so a good reply from it means the connection and sign-in are fine.
Why would a Sume tool be missing on a connected server?
Hosted Sume MCP defaults to read-only visibility under OAuth mcp:read: mutating and paid tools are hidden until the session has mcp:write or an API key. The quickstart adds that write and paid tools such as generate_image return insufficient_scope with read access only. So a resumed session that connected fine can still lack generate_image if Write was left off at consent.
The fix is to grant Write on the consent screen, or to use an API-key remote MCP session. Details are in MCP tools and gates.
What should I run after a resume?
Call mcp_health first: it is read-only and says whether the session is authenticated. Then call tools_list, which lists every tool visible to this session with safety metadata. If the tool you need is absent there, no amount of waiting helps; change the scopes. If tools_list itself fails with the same error, the server was not connected yet, so retry or run /mcp reconnect all.
Sources
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