Claude Code 2.1.296: MCP tool names over 128 characters, and Sume's
Claude Code 2.1.296 leaves out an MCP tool whose name exceeds 128 characters. The longest tool name in Sume's hosted list is 28, so none are near it.
No Sume tool is close to Claude Code's 128-character limit. Claude Code 2.1.296 (October 9, 2026) fixed a bug where an MCP tool with a name longer than 128 characters made every request fail; that tool is now left out and an MCP error names it. The longest names in Sume's documented hosted tool list are 28 characters, for example video-caption-overlay_create and avatar-image-to-video_create.
What changed
Before 2.1.296 one over-long name could take down the whole session. Now the single tool is dropped and the error names it, so the rest keep working.
| Item | Value |
|---|---|
| Claude Code limit | 128 characters (2.1.296) |
| Behavior above the limit | Tool left out; MCP error names it |
| Longest Sume name in the docs list | 28 characters |
| Sume names that use hyphens | image-models_list, avatar-videos_create and similar |
What to check
The changelog does not say whether the 128 counts the server prefix, so do not assume that your own server names add nothing. Sume's names plus a short server alias still leave a wide margin. To see the live names in your session call tools_list; the hosted inventory is on the tools and gates page.
If you wrap Sume tools in your own MCP server, keep wrapper names short and do not append ids or timestamps to them.
How to check your own list
Count names rather than trust a memory of them. Call tools_list in a connected session, take each tool name, and print any that are longer than 100 characters; for Sume the maximum will be well below that. The point of a margin is that a wrapper, a proxy or a naming scheme you add later can only lengthen names.
The changelog entry also matters for what it says about failure: the offending tool is left out and an MCP error names it. If a Sume tool you expect is missing after an upgrade, read the MCP error before you suspect a scope problem. Under OAuth, a missing paid tool usually means the session was granted mcp:read only, which the OAuth page describes.
- Missing paid tool + read scope: expected.
- Missing tool + MCP error naming it: a name problem.
- Missing tool and neither: call tools_list and compare with the docs inventory.
Sources
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