Spreadsheet Formula Helper

Produce reliable spreadsheet formulas with explanations.

• Leverage native parallel subagent dispatch and 200k+ context windows where available.

Inputs to gather

• Platform (Excel/Sheets), locale (comma vs. semicolon separators), sample data layout (headers, ranges), expected outputs, and constraints (volatile functions allowed?).
• Provide small example rows and the desired result for them.

Workflow

1. Restate the problem with explicit ranges and sheet names; propose a minimal sample to verify.
2. Draft formula(s); when dynamic arrays are available, prefer them over copy-down formulas.
3. Explain how it works and where to place it; include named ranges if helpful.
4. Edge cases: blank rows, mixed types, timezone/date quirks, duplicates; offer guardrails (e.g., IFERROR, LET, LAMBDA).
5. Variants: if porting between Excel and Sheets, provide both versions.

Output

• Primary formula, short explanation, and a 2-3 row worked example showing inputs to outputs.
• Optional: quick troubleshooting checklist for common errors.

MCP Fallback – Native Automation

When MCP is unavailable, use native automation: local spreadsheet formulas, openpyxl for workbook inspection, CSV fixtures for examples, and manual recalculation notes for functions the local engine cannot evaluate. Preserve locale separators, absolute references, dynamic arrays, and Excel-vs-Sheets differences before claiming success.

Cross-Client Portability

This skill is written to stay usable across GitHub Copilot, Claude Code, and Codex.

• GitHub Copilot: keep the folder in a Copilot-visible skill path or wrap the workflow in project instructions when folder discovery is unavailable.
• Claude Code: keep the folder in a local skills directory or a compatible plugin source.
• Codex: install or sync the folder into $CODEX_HOME/skills/spreadsheet-formula-helper and restart Codex after major changes.

MCP Availability And Fallback

Preferred MCP Server: None required

• Fallback prompt: "Use the Spreadsheet Formula Helper skill without MCP. Rely on its local instructions, bundled resources, standard shell or editor tools, and direct verification. Show the evidence used before concluding."
• Do not claim an MCP operation was used when the active host does not expose it.
• Treat local files, tests, rendered outputs, logs, or screenshots as the fallback evidence path.

Anti-Patterns

• Treating source content as already clean: Formatting automation will happily preserve broken or inconsistent input.
• Skipping an open-file verification pass: Documents and spreadsheets often fail in the destination app, not in the script output.
• Automating irreversible edits without checkpoints: A small mapping mistake can affect an entire workbook or document.

Verification Protocol

Before claiming the spreadsheet-formula-helper workflow succeeded:

1. Pass/fail: The request matches this skill's documented activation boundary.
2. Pass/fail: Required inputs, dependencies, and safety checks were resolved or reported as blockers.
3. Pass/fail: The narrowest relevant workflow was completed without inventing unavailable tools or results.
4. Pass/fail: Output was checked with the most relevant local test, inspection, render, or source evidence.
5. Pressure test: Repeat the decision with the preferred integration unavailable and confirm the fallback remains safe and actionable.
6. Success metric: The result, evidence, and any unverified limitation are explicit enough for another agent to reproduce.

Related Skills

• documentation-authoring: Use it when the workflow also needs drafting structured technical or product documents.
• notion-docs: Use it when the workflow also needs Notion page and database publishing workflows.
• pdf: Use it when the workflow also needs PDF extraction, generation, and layout-aware review.
• word-document: Use it when the workflow also needs Word document authoring and formatting workflows.