fix: handle missing arguments in MCP tool calls to prevent GUI crash

[echoVic]

Summary

When a tool request arrives without an arguments field (valid for no-arg tools like MATLAB toolbox detection), the desktop renderer crashes with:

Cannot convert undefined or null to object

Root Cause

In ui/desktop/src/components/ToolCallWithResponse.tsx, the getToolDescription() function casts toolCall.arguments directly without a fallback:

const args = toolCall.arguments as Record<string, ToolCallArgumentValue>;

When arguments is undefined (valid per MCP spec for no-arg tools), the subsequent Object.entries(args) call in the default branch throws.

Fix

Add nullish coalescing default so args safely falls back to an empty object:

const args = (toolCall.arguments ?? {}) as Record<string, ToolCallArgumentValue>;

This is consistent with how the same file already handles arguments elsewhere (e.g., line 469 uses optional chaining, line 815 uses && guard).

Testing

• No-arg tool calls (e.g. matlab__detect_matlab_toolboxes) now render without crashing
• Tools with arguments continue to work as before (all existing switch cases access args.* properties which safely return undefined on an empty object)

Fixes #7116

[DOsinga]

oof this code could do with some cleanup, but thanks for the fix!

[DOsinga]

can you take care of the DCO thing so we can merge?

[echoVic]

Done! I've amended the commit with the DCO sign-off. Should be good to merge now. 🙏

[DOsinga]

thank you!