MCP server name over 64 chars: all its tools are silently dropped, and the server still shows connected #53400

Description

If an MCP server's name is longer than 64 characters (after _ normalization), none of its tools get registered. GET /api/mcp still says connected, and the only sign is one ERROR log line per tool. namespaceError in tool.ts requires each namespace segment to match ^[A-Za-z0-9_-]{1,64}$, but McpTool.namespace (tool/mcp.ts:16) only replaces characters and never shortens the name. #51207 raised tool names to 128 chars, but the namespace limit is still 64.

We hit this through T3 Code, which names its per-thread server t3-code-<threadId> (96+ chars), so the agent gets none of T3's tools.

Suggested fix: shorten long names in McpTool.namespace, for example the first 55 chars + _ + an 8-char hash of the full name. Permission names built from it (McpTool.name) would have to use the same short form. Or at least show the rejection in /api/mcp.

Plugins

none

OpenCode version

2.0.22. The code is the same in 2.0.23 and on v2 @ ef07075.

Steps to reproduce

1. Project opencode.json, with a 65-char server name and any stdio MCP server (we used a 30-line Python one):

   {"mcp":{"servers":{"srv_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa":{"type":"local","command":["python3","mcp_server.py"]}}}}

2. Run opencode serve, then GET /api/mcp?directory=<project>. The server is listed as connected.
3. opencode.log then shows, for every tool:

   level=ERROR message="Skipping invalid tool registration" name=get_vault_code namespace=srv_aaaa…aaa error="Invalid tool namespace: \"srv_aaaa…aaa\""
   

   None of the server's tools reach the model. With a short name, the same server works.

Screenshot and/or share link

n/a

Operating System

NixOS 26.11 (Linux 6.18)

Terminal

n/a (opencode serve)