feat: improve error handling for empty or malformed tool files

[FiammaMuscari]

Closes #464

This PR improves error handling when loading tool files.

• Skips empty files and missing default exports with clear, friendly warnings
• Includes the file path in error messages for invalid tool implementations
• Preserves full stack traces for real syntax/import errors
• Adds a startup summary for skipped tools
• Avoids repeated warning spam

Tests:

• added regression tests for skipped tool files
• ensured file path is included in failure cases
• verified real errors still surface correctly

[greptile-apps]

PR author is not in the allowed authors list.

[vercel]

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[0xKoller]

Thanks for the PR @FiammaMuscari!

Looks promising overall. Before a thorough review, could you please add:

• A concrete usage example
• Screenshots
• Documentation updates

Also it seems that some code has been dragged from the #527 , please remove.

[FiammaMuscari]

Updated the PR to remove the unrelated code that had been dragged from #527.

Also added:

• a concrete usage example
• a documentation update in the Tools docs
• a terminal screenshot showing the new startup warning for an empty tool file

Example output:
[xmcp] Failed to load tool file: src/tools/draft.ts
-> File is empty.
[xmcp] 1 tool skipped due to empty files or missing default exports

Real syntax/import errors are still preserved and surface with full stack traces; only empty files and missing default exports are handled gracefully.

[0xKoller]

Good path! There are some changes that need to be done but besides that everything seems good.

[FiammaMuscari]

Moved this to a Troubleshooting section in the Tools docs in eb3d9cc.

[valebearzotti]

Hey @FiammaMuscari !

I personally really like this implementation and it'd be great to see the same for resources & prompts. Can we do the same for the other components? And maybe put all loaders (tool-loader, resource-, prompt-) in the same folder?

I'm gonna approve this PR, please continue with the remaining changes in a separate one. Thanks!

[FiammaMuscari]

Great, I’ll address this in a follow-up PR

[FiammaMuscari]

Follow-up PR: #538

This continues the review feedback from #528 by extending the same graceful startup handling to prompts and resources in a separate, minimal PR.