spreadsheet-kit MCP server

agent-spreadsheet

agent-spreadsheet is the tool interaction service for agent-based spreadsheet usage.

It gives agents a safe, inspectable, token-efficient way to read, analyze, mutate, verify, and operationalize Excel workbooks without falling back to brittle UI automation.

If you want an agent to work with spreadsheets like a real system instead of a screenshot puppet, this is the stack.

What this project is

agent-spreadsheet ships a unified spreadsheet interaction layer across three surfaces:

The WASM build (agent-spreadsheet-wasm) is the SDK's local runtime, not a separate product surface: JS and TypeScript code targets one object model and the execution substrate (server vs embedded engine) is a configuration choice.

In 0.16 these surfaces share the resident Rust document/evaluator runtime and 32-operation registry. Explicit native sessions automatically start a private journal-backed host. SDK/WASM and genuine just-bash sessions retain their history in memory; XLSX export saves a document snapshot, not a restartable session journal. Warm edit/recalculate/read loops avoid XLSX serialization and repeated evaluator ingestion. See runtime guarantees and limits and the SDK/just-bash examples.

Supported workbook modes:

• .xlsx / .xlsm — read + write
• .xls / .xlsb — discovery/read-oriented workflows only

Powered by Formualizer

Default in-process calculation uses Formualizer — a permissively licensed (MIT/Apache-2.0) spreadsheet engine written in Rust: formula parsing, dependency-graph recalculation, 400+ Excel functions, dynamic arrays, and deterministic evaluation built for agents. No Excel COM or headless LibreOffice is required. Optional LibreOffice integration remains available, but Formualizer is the release-critical backend.

That native engine is why this project can offer what most spreadsheet tooling for agents cannot: recalculate the actual workbook, trace which cells changed and why, and prove it — not just read cached values or push blind edits.

Embedding spreadsheet logic in your own product rather than driving workbooks as an agent? Use Formualizer directly (Rust, Python, JS/WASM).

Why agents use agent-spreadsheet

Built for tool use, not just humans

• deterministic JSON contracts
• schema and example discovery from the CLI itself
• explicit pagination and compact output modes
• machine-readable warnings and error envelopes

Shortened. The full README is on GitHub.