feat: replace verbose Excel reader with sparse output tool (92.5% reduction)

[MariusWilsch]

Summary

Replaces the verbose read_data_from_excel tool with a new read_excel tool that reduces output by 92.5% (from 31,362 to 2,362 characters) by returning only non-null cells without validation metadata.

Task Link

Task: User feedback - Excel MCP tool returns excessive metadata making it unusable for AI agents needing clean data

How to Test

1. Install dependencies and start the server:

   uv sync
   uv run python -m excel_mcp stdio

2. Test with the included MailAvis.xlsx file to see the reduction:

   # Compare old vs new output size
   uv run python -c "
   from src.excel_mcp.data import read_excel_range_with_metadata, read_excel_sparse
   import json
   
   # OLD verbose function (still available for comparison)
   old = read_excel_range_with_metadata('MailAvis.xlsx', 'Tabelle1', 'A1:J20')
   old_json = json.dumps(old, indent=2, default=str)
   
   # NEW sparse function
   new = read_excel_sparse('MailAvis.xlsx', 'Tabelle1', 'A1:J20') 
   new_json = json.dumps(new, indent=2, default=str)
   
   print(f'Old tool: {len(old_json):,} characters, {len(old["cells"])} cells')
   print(f'New tool: {len(new_json):,} characters, {len(new["cells"])} cells')
   print(f'Reduction: {(1 - len(new_json)/len(old_json))*100:.1f}%')
   "

3. Verify the new MCP tool returns only non-null cells:

   • Connect an MCP client to the server
   • Call read_excel with any Excel file containing sparse data
   • Observe only cells with values are returned (no null cells)

Expected Result:

• Output shows ~92.5% character reduction
• Only 22 non-null cells returned instead of 200 total cells
• No validation metadata in the output (clean structure with just address, value, row, column)

⚠️ Deployment Notes

BREAKING CHANGE:

• The read_data_from_excel tool has been removed and replaced with read_excel
• Any MCP clients using the old tool name will need to update to the new name
• The output structure is cleaner but different (no validation metadata)

Migration path:

• Old tool: mcp__excel__read_data_from_excel
• New tool: mcp__excel__read_excel
• Output format: Still JSON but only non-null cells, no validation field

🤖 Generated with Claude Code