Bug Report
Environment
- Windows 11 Pro (build 26200)
- Claude Code CLI 2.1.121, Claude Desktop (MSIX-packaged signed
.exe from claude.ai/download)
- simulink-agentic-toolkit v0.4.0 + model-based-design-core v0.2.0
- matlab-mcp-core-server v0.8.1, MATLABMCPCoreServerToolkit.mltbx v0.1.0
- MATLAB R2025b primary; R2023b and R2021b also installed
Installation steps taken
- Ran the automated
simulink-agentic-toolkit-setup in Claude Code CLI. Worked as documented.
- Asked Claude Code to extend the MCP setup to Claude Desktop. Required ad-hoc diagnosis and a
--log-folder workaround (issue 1).
- Installed
matlab-core@matlab-agentic-toolkit skills only via the marketplace, not modifying the MCP.
Issue 1: Setup skill does not handle Claude Desktop
The setup skill registers the MCP server via claude mcp add-json -s user, which writes to Claude Code's config under ~/.claude/. Claude Desktop reads MCP config from a different file: %APPDATA%\Roaming\Claude\claude_desktop_config.json. After running the automated setup, Desktop has no simulink MCP server.
Adding the entry manually to that file is not sufficient. The server fails immediately:
ERROR Failed to connect to watchdog socket: access denied for socket file
ERROR Server failed with unexpected error: access denied for socket file
Cause: Claude Desktop is MSIX-packaged. Spawned children inherit an 8.3 short-form TEMP (e.g. C:\Users\USERNA~1\AppData\Local\Temp\). The MCP server's watchdog creates a .sock AF_UNIX socket file inside that temp dir. Windows AF_UNIX connect() does not resolve socket paths through 8.3 short-name components, so the main process cannot connect. The CLI does not hit this because it is not MSIX-packaged and inherits a long-form TEMP.
Workaround applied: add --log-folder=C:/McpLogs to args so the watchdog socket lives outside the 8.3-poisoned tree.
Suggested fix: detect Claude Desktop in the setup skill, write claude_desktop_config.json accordingly, and on Windows always pass --log-folder=<long-form-path>. This would also justify a Tested status for Claude Desktop in the platform table.
Issue 2: R2023a floor blocks older-MATLAB workflows even for MATLAB-only workflows
MATLABMCPCoreServerToolkit.mltbx (installed by this toolkit) ships a shareMATLABSession wrapper that hard-fails below R2023a:
>> shareMATLABSession
Error using mcpcoreserver.internal.connector.internal.apikeymanager.DefaultAPIKeyManager/getAPIKey
MCP server requires MATLAB R2023a or later.
This locks the entire MCP path to R2023a+, even for users who only want matlab-agentic-toolkit skills.
Practical impact: a user with both toolkits installed cannot point the MCP at R2021b/R2022b, even when they have no Simulink dependency in that session. It would be great to support R2021b for MATLAB only workflows.
Suggested fix: allow the MCP server / supporting toolbox to operate against older MATLAB versions in a MATLAB-only mode where Simulink-specific behaviour is gated off.
Issue 3: Skills do not appear in Claude Desktop's Customize panel
Skills from this toolkit are functional in Claude Desktop. Slash invocation works, and Claude self-triggers them when a description matches. But they do not appear in the Customize panel's skill list. Skills from plugins using the conventional skills/ folder layout (e.g. Superpowers) do appear.
Cause: this toolkit uses a skills-catalog/<plugin>/ layout, declared via the "skills" field in marketplace.json. The Customize panel scanner appears to only walk the conventional skills/ directory and does not honour the override.
This is a UI/discoverability gap, not a functional gap. New users browsing Customize cannot see what skills are available.
Suggested fix: at minimum, document this in the README so users do not assume the install is broken. Optionally, ship a top-level skills/ directory (or symlink at install time) per plugin for compatibility. Worth raising with Anthropic in parallel so the Customize scanner honours marketplace.json's "skills" field.
Generated by Claude.
Additional Context
No response
Bug Report
Environment
.exefrom claude.ai/download)Installation steps taken
simulink-agentic-toolkit-setupin Claude Code CLI. Worked as documented.--log-folderworkaround (issue 1).matlab-core@matlab-agentic-toolkitskills only via the marketplace, not modifying the MCP.Issue 1: Setup skill does not handle Claude Desktop
The setup skill registers the MCP server via
claude mcp add-json -s user, which writes to Claude Code's config under~/.claude/. Claude Desktop reads MCP config from a different file:%APPDATA%\Roaming\Claude\claude_desktop_config.json. After running the automated setup, Desktop has nosimulinkMCP server.Adding the entry manually to that file is not sufficient. The server fails immediately:
Cause: Claude Desktop is MSIX-packaged. Spawned children inherit an 8.3 short-form
TEMP(e.g.C:\Users\USERNA~1\AppData\Local\Temp\). The MCP server's watchdog creates a.sockAF_UNIX socket file inside that temp dir. Windows AF_UNIXconnect()does not resolve socket paths through 8.3 short-name components, so the main process cannot connect. The CLI does not hit this because it is not MSIX-packaged and inherits a long-formTEMP.Workaround applied: add
--log-folder=C:/McpLogsto args so the watchdog socket lives outside the 8.3-poisoned tree.Suggested fix: detect Claude Desktop in the setup skill, write
claude_desktop_config.jsonaccordingly, and on Windows always pass--log-folder=<long-form-path>. This would also justify a Tested status for Claude Desktop in the platform table.Issue 2: R2023a floor blocks older-MATLAB workflows even for MATLAB-only workflows
MATLABMCPCoreServerToolkit.mltbx(installed by this toolkit) ships ashareMATLABSessionwrapper that hard-fails below R2023a:This locks the entire MCP path to R2023a+, even for users who only want
matlab-agentic-toolkitskills.Practical impact: a user with both toolkits installed cannot point the MCP at R2021b/R2022b, even when they have no Simulink dependency in that session. It would be great to support R2021b for MATLAB only workflows.
Suggested fix: allow the MCP server / supporting toolbox to operate against older MATLAB versions in a MATLAB-only mode where Simulink-specific behaviour is gated off.
Issue 3: Skills do not appear in Claude Desktop's Customize panel
Skills from this toolkit are functional in Claude Desktop. Slash invocation works, and Claude self-triggers them when a description matches. But they do not appear in the Customize panel's skill list. Skills from plugins using the conventional
skills/folder layout (e.g. Superpowers) do appear.Cause: this toolkit uses a
skills-catalog/<plugin>/layout, declared via the"skills"field inmarketplace.json. The Customize panel scanner appears to only walk the conventionalskills/directory and does not honour the override.This is a UI/discoverability gap, not a functional gap. New users browsing Customize cannot see what skills are available.
Suggested fix: at minimum, document this in the README so users do not assume the install is broken. Optionally, ship a top-level
skills/directory (or symlink at install time) per plugin for compatibility. Worth raising with Anthropic in parallel so the Customize scanner honoursmarketplace.json's"skills"field.Generated by Claude.
Additional Context
No response