spreadsheet-kit

spreadsheet-kit 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

spreadsheet-kit ships a unified spreadsheet interaction layer across four surfaces:

Supported workbook modes:

• .xlsx / .xlsm — read + write

• .xls / .xlsb — discovery/read-oriented workflows only

Related MCP server: fcp-sheets

Why agents use spreadsheet-kit

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

Safe mutation, not blind mutation

• dry-run first workflows

• stateless output modes and overwrite safety

• event-sourced session editing

• verification surfaces for proving downstream outcomes

• structural impact analysis before risky workbook changes

Spreadsheet-aware, not generic file editing

• region detection

• table and footer-aware append helpers

• template row / row band cloning

• formula-specific replace and diagnostics

• named range CRUD

• recalculation + diff + proof flows

Good agent ergonomics

• nested command groups with legacy alias compatibility

• token-efficient reads

• exact-cell inspection and layout inspection

• workflow helpers for the repetitive parts agents usually get wrong

What is new / what makes this stack different

The current surface is much stronger than a plain “read some cells” tool. Major capabilities now include:

• asp as the primary CLI with agent-spreadsheet preserved as a compatibility alias

• grouped verification via asp verify proof and asp verify diff

• preview-first workflow helpers for:

  • write append

  • write clone-template-row

  • write clone-row-band

• formula-safe batch workflows with parse-policy diagnostics

• cell/layout/export/import inspection surfaces

• named range management (write name define|update|delete)

• formula-only replacement (write formulas replace)

• event-sourced session editing with log, branch, undo/redo, fork, apply, and materialize

• SheetPort manifest lifecycle + execution for contract-driven spreadsheet automation

Install

npm (recommended for CLI)

npm i -g agent-spreadsheet
asp --help

Installs both:

• asp — primary command

• agent-spreadsheet — compatibility alias

Downloads a prebuilt native binary for your platform. No Rust toolchain required.

Cargo

# CLI
cargo install spreadsheet-kit --features recalc --bin asp --bin agent-spreadsheet

# MCP server
cargo install spreadsheet-mcp

Formualizer (the native Rust recalc engine) is included by default.

Docker

# Read-only / slim
docker pull ghcr.io/psu3d0/spreadsheet-mcp:latest

# Write + recalc + screenshots
docker pull ghcr.io/psu3d0/spreadsheet-mcp:latest-full

JavaScript SDK

npm i spreadsheet-kit-sdk

Prebuilt binaries

Download from GitHub Releases.

Published native assets include:

• Linux x86_64

• macOS x86_64

• macOS arm64

• Windows x86_64

Start here: the core workflows

1) Orient the workbook before reading cells

# What sheets are here?
asp read sheets data.xlsx

# What regions/tables/parameter blocks does this sheet contain?
asp read overview data.xlsx "Model"

# What named items are available?
asp read names data.xlsx

# Read a structured region as a table
asp read table data.xlsx --sheet "Model"

2) Inspect exactly what an agent needs

# Raw values for exact ranges
asp read values data.xlsx Model A1:C20

# Detail-view for targeted cells (value / formula / cached / style triage)
asp read cells data.xlsx Model B2 D10:F12

# Layout-aware rendering for a bounded range
asp read layout data.xlsx Model --range A1:H30 --render both

# Export a bounded range to csv or grid json
asp read export data.xlsx Model A1:H30 --format csv --output model.csv

3) Do a safe stateless edit → recalc → proof → diff loop

asp workbook copy data.xlsx /tmp/draft.xlsx
asp write cells /tmp/draft.xlsx Inputs "B2=500" "C2==B2*1.1"
asp workbook recalculate /tmp/draft.xlsx
asp verify proof data.xlsx /tmp/draft.xlsx --targets Summary!B2,Summary!B3 --named-ranges
asp verify diff data.xlsx /tmp/draft.xlsx --details --limit 50

A representative label-mode lookup:

asp analyze find-value data.xlsx "Net Income" --mode label --label-direction below

4) Preview structural risk before mutating the workbook

asp analyze ref-impact data.xlsx --ops @structure_ops.json --show-formula-delta

This is intentionally read-only. It surfaces shifted spans, absolute-reference warnings, token counts, and optional before/after formula samples.

5) Use workflow helpers instead of reinventing row logic

# Stateless batch writes
asp write batch transform data.xlsx --ops @ops.json --dry-run
asp write batch style data.xlsx --ops @style_ops.json --dry-run

# Append rows into a detected region or table, respecting footer rows when present
asp write append data.xlsx --sheet Revenue --table-name RevenueTable --from-csv rows.csv --header --dry-run

# Clone one template row with preview-first planning
asp write clone-template-row data.xlsx --sheet Inputs --source-row 8 --after 8 --count 3 --dry-run

# Clone a contiguous row band repeatedly
asp write clone-row-band data.xlsx --sheet Forecast --source-rows 12:16 --after 16 --repeat 4 --dry-run

6) Use a stateful session when the edit story gets complex

asp session start --base data.xlsx --workspace .
asp session op --session <id> --ops @edit.json --workspace .
asp session apply --session <id> <staged_id> --workspace .
asp session materialize --session <id> --output result.xlsx --workspace .

And when you need proper history and branching:

asp session log --session <id> --workspace .
asp session fork --session <id> scenario-a --workspace .
asp session undo --session <id> --workspace .
asp session redo --session <id> --workspace .
asp session checkout --session <id> <op_id> --workspace .

7) Turn workbook interfaces into contracts with SheetPort

# Discover candidate ports from workbook structure
asp sheetport manifest candidates model.xlsx

# Validate or normalize a manifest
asp sheetport manifest validate manifest.yaml
asp sheetport manifest normalize manifest.yaml

# Bind-check a workbook against a manifest
asp sheetport bind-check model.xlsx manifest.yaml

# Execute the manifest with JSON inputs
asp sheetport run model.xlsx manifest.yaml --inputs @inputs.json

CLI overview

The primary CLI is asp.

agent-spreadsheet remains available as a compatibility alias, so both of these are valid:

asp read sheets data.xlsx
agent-spreadsheet read sheets data.xlsx

Preferred command groups

• asp read ...

• asp analyze ...

• asp write ...

• asp workbook ...

• asp verify ...

• asp session ...

• asp sheetport ...

Legacy aliases

Legacy flat commands are still normalized to the new nested surface where practical. That makes migration easier for older prompts, docs, and automation.

Discoverability built into the CLI

When an agent is unsure of payload shape, it can ask the tool directly:

asp schema write batch transform
asp example write batch transform
asp schema session op transform.write_matrix
asp example session op transform.write_matrix

This is a core design principle: the surface should explain itself to the agent.

Command families

read — extraction and inspection

Why these matter for agents

Agents rarely need “the whole spreadsheet.” They need:

• the right region

• the right page

• the right cells

• just enough layout to understand intent

That is why the read surface combines region detection, structured reads, detail inspection, and explicit continuation.

analyze — search, diagnostics, and impact understanding

Why this matters

Headless spreadsheet automation wins when it can explain consequences, not just execute mutations. ref-impact, formula-trace, and grouped diagnostics are all part of that story.

write — safe mutations and workflow helpers

Safety model

Most mutating commands support a strict mode matrix:

• --dry-run

• --in-place

• --output <PATH>

This matters for agents because it allows:

• dry-run planning

• non-destructive execution

• explicit overwrite control

Formula maintenance

Formula mutation is now a first-class surface:

asp write formulas replace data.xlsx Sheet1 --find '$64' --replace '$65' --dry-run
asp write formulas replace data.xlsx Sheet1 --find 'Sheet1!' --replace 'Sheet2!' --range A1:Z100 --output fixed.xlsx

Named range maintenance

asp write name define data.xlsx RevenueInput 'Inputs!$B$2'
asp write name update data.xlsx RevenueInput 'Inputs!$B$2:$B$4' --in-place
asp write name delete data.xlsx RevenueInput --in-place

workbook — file-level flows

verify — proof, not vibes

Why verification matters

Most spreadsheet automation tools stop at “the edit applied.”

spreadsheet-kit goes further:

• did the target cells change the way we expected?

• did the workbook introduce new errors?

• which changes were direct edits vs recalculation fallout?

• what changed overall, grouped in a way an agent can reason about?

This verification layer is a big part of why this project is a serious agent substrate rather than a utility script.

session — event-sourced stateful editing

The session surface is for workflows that are too complex for a single stateless write.

What sessions give you

• persistent editing state

• staged dry-run operations

• compare-and-swap apply semantics

• logs and replayability

• branch/switch/fork flows

• undo / redo / checkout

• explicit materialization back to a workbook file

Canonical loop

asp session start --base model.xlsx --workspace .
asp session op --session <id> --ops @ops.json --workspace .
asp session apply --session <id> <staged_id> --workspace .
asp session materialize --session <id> --output result.xlsx --workspace .

History and branching

asp session log --session <id> --workspace .
asp session branches --session <id> --workspace .
asp session fork --session <id> experiment-b --workspace .
asp session switch --session <id> experiment-b --workspace .
asp session undo --session <id> --workspace .
asp session redo --session <id> --workspace .
asp session checkout --session <id> <op_id> --workspace .

Use sessions when you want repeatability, auditability, and multi-step safety.

sheetport — spreadsheet interfaces as executable contracts

SheetPort is the workflow surface for turning workbook inputs/outputs into explicit machine contracts.

Manifest lifecycle

asp sheetport manifest candidates model.xlsx
asp sheetport manifest schema
asp sheetport manifest validate manifest.yaml
asp sheetport manifest normalize manifest.yaml

Bind-check + run

asp sheetport bind-check model.xlsx manifest.yaml
asp sheetport run model.xlsx manifest.yaml --inputs @inputs.json --freeze-volatile

Use this when you want a workbook to behave less like an opaque file and more like a declared service interface.

Output contracts for agents

Canonical vs compact shapes

All commands default to JSON. Many also support:

--shape canonical
--shape compact

Policy:

• canonical keeps the full stable schema

• compact removes wrapper noise where the contract allows it while preserving continuation fields and command-specific semantics

Shape policy:

• Canonical (default): preserve the full response schema.

• range-values: returns a stable values: [...] envelope in both canonical and compact modes.

• range-values default encoding: dense JSON (dense.encoding = "dense_v1") with dictionary + run-length row_runs.

• range-values --include-formulas: includes sparse formula coordinates in dense mode (dense.formulas), or a matrix in explicit json format.

• read-table and sheet-page: compact preserves the active branch and continuation fields (next_offset, next_start_row).

• formula-trace compact: omits per-layer highlights while preserving layers and next_cursor.

Deterministic pagination loops

# sheet-page continuation
asp read page data.xlsx Sheet1 --format compact --page-size 200
asp read page data.xlsx Sheet1 --format compact --page-size 200 --start-row 201

# read-table continuation
asp read table data.xlsx --sheet "Sheet1" --table-format values --limit 200 --offset 0
asp read table data.xlsx --sheet "Sheet1" --table-format values --limit 200 --offset 200

sheet-page machine contract

• Inspect top-level format before reading payload fields.

• format=full: read top-level rows plus optional header_row and next_start_row.

• format=compact: read compact.headers, compact.header_row, compact.rows plus optional next_start_row.

• format=values_only: read values_only.rows plus optional next_start_row.

• Continuation is always driven by top-level next_start_row when present.

• Global --shape compact preserves the active sheet-page branch; it does not flatten sheet-page payloads.

Machine continuation example:

1. Request page 1 without --start-row.

2. If next_start_row is present, call sheet-page again with --start-row <next_start_row>.

3. Stop when next_start_row is omitted.

Self-describing payloads

When the agent is unsure what to send, ask for a schema or example:

asp schema write batch rules
asp example write batch rules
asp schema session op structure.insert_rows
asp example session op structure.insert_rows

Batch payload examples

All batch payloads use a top-level envelope object. Most commands require {"ops":[...]}; column-size-batch prefers {"sheet_name":"...","ops":[...]} and also accepts per-op sheet_name inside {"ops":[...]}.

transform-batch payloads (@transform_ops.json)

• Minimal: {"ops":[{"kind":"fill_range","sheet_name":"Sheet1","target":{"kind":"range","range":"B2:B4"},"value":"0"}]}

• Advanced: {"ops":[{"kind":"replace_in_range","sheet_name":"Sheet1","target":{"kind":"region","region_id":1},"find":"N/A","replace":"","match_mode":"contains","case_sensitive":false,"include_formulas":true}]}

style-batch payloads (@style_ops.json)

• Minimal: {"ops":[{"sheet_name":"Sheet1","target":{"kind":"range","range":"B2:B2"},"patch":{"font":{"bold":true}}}]}

• Advanced: {"ops":[{"sheet_name":"Sheet1","target":{"kind":"cells","cells":["B2","B3"]},"patch":{"number_format":"$#,##0.00","alignment":{"horizontal":"right"}},"op_mode":"merge"}]}

write batch formula-pattern payloads (@formula_ops.json)

• Minimal: {"ops":[{"sheet_name":"Sheet1","target_range":"C2:C4","anchor_cell":"C2","base_formula":"B2*2"}]}

• Advanced: {"ops":[{"sheet_name":"Sheet1","target_range":"C2:E4","anchor_cell":"C2","base_formula":"B2*2","fill_direction":"both","relative_mode":"excel"}]}

• relative_mode valid values: excel, abs_cols, abs_rows

structure-batch payloads (@structure_ops.json)

• Minimal: {"ops":[{"kind":"rename_sheet","old_name":"Summary","new_name":"Dashboard"}]}

• Advanced: {"ops":[{"kind":"copy_range","sheet_name":"Sheet1","dest_sheet_name":"Summary","src_range":"A1:C4","dest_anchor":"A1","include_styles":true,"include_formulas":true}]}

column-size-batch payloads (@column_size_ops.json)

• Minimal (preferred): {"sheet_name":"Sheet1","ops":[{"range":"A:A","size":{"kind":"width","width_chars":12.0}}]}

• Advanced (preferred): {"sheet_name":"Sheet1","ops":[{"target":{"kind":"columns","range":"A:C"},"size":{"kind":"auto","min_width_chars":8.0,"max_width_chars":24.0}}]}

• Also accepted (harmonized shape): {"ops":[{"sheet_name":"Sheet1","range":"A:A","size":{"kind":"width","width_chars":12.0}}]}

sheet-layout-batch payloads (@layout_ops.json)

• Minimal: {"ops":[{"kind":"freeze_panes","sheet_name":"Sheet1","freeze_rows":1,"freeze_cols":1}]}

• Advanced: {"ops":[{"kind":"set_page_setup","sheet_name":"Sheet1","orientation":"landscape","fit_to_width":1,"fit_to_height":1}]}

rules-batch payloads (@rules_ops.json)

• Minimal: {"ops":[{"kind":"set_data_validation","sheet_name":"Sheet1","target_range":"B2:B4","validation":{"kind":"list","formula1":"\"A,B,C\""}}]}

• Advanced: {"ops":[{"kind":"set_conditional_format","sheet_name":"Sheet1","target_range":"C2:C10","rule":{"kind":"expression","formula":"C2>100"},"style":{"fill_color":"#FFF2CC","bold":true}}]}

write batch formula-pattern clears cached results for touched formula cells; run workbook recalculate to refresh computed values.

Formula parse policy

Formula-aware commands support:

--formula-parse-policy fail|warn|off

• fail — abort

• warn — continue and attach grouped diagnostics

• off — skip silently

This lets agents choose between strictness and progress depending on the workflow.

CLI reference excerpts

• read values <file> <sheet> <range> [range...] [--format dense\|json\|values\|csv] [--include-formulas]

• read cells <file> <sheet> <target> [target...] [--include-empty]

• read page <file> <sheet> --format <full|compact|values_only> [--start-row ROW] [--page-size N]

• workbook create <path> [--sheets Inputs,Calc,...] [--overwrite]

• analyze find-value <file> <query> [--sheet S] [--mode value\|label] [--label-direction right\|below\|any]

• write batch transform <file> --ops @ops.json (--dry-run\|--in-place\|--output PATH)

Formula write-path provenance (write_path_provenance)

Formula-writing commands emit optional provenance metadata for troubleshooting:

• written_via: write path (edit, transform_batch, apply_formula_pattern)

• formula_targets: sheet/cell or sheet/range targets touched by formula writes

Debug compare workflow:

1. Apply the same formula target via two paths.

2. Compare write_path_provenance.written_via and formula_targets in responses.

3. Use inspect-cells plus recalculate to compare resulting behavior.

Financial presentation starter defaults

• Keep label columns (often column A) explicitly sized (roughly 24–36 chars) to prevent clipping.

• Apply consistent number formats by semantic type:

  • Currency: "$"#,##0.00_);[Red]("$"#,##0.00)

  • Percent: 0.0%

  • Integer/count: #,##0

• Apply sheet-layout-batch freeze panes after header layout stabilizes.

JSON output is compact by default; use --quiet to suppress warnings. Global --output-format csv is currently unsupported; use command-specific CSV options like read table --table-format csv.

MCP server quickstart

The MCP surface is the stateful server version of spreadsheet-kit.

Use it when you want:

• workbook caching across calls

• fork lifecycle instead of stateless file replacement

• multi-turn agent workflows

• screenshots and richer server-side orchestration

Claude Code / Claude Desktop

Add to ~/.claude.json or project .mcp.json:

{
  "mcpServers": {
    "spreadsheet": {
      "command": "spreadsheet-mcp",
      "args": ["--workspace-root", "/path/to/workbooks", "--transport", "stdio"]
    }
  }
}

Docker

{
  "mcpServers": {
    "spreadsheet": {
      "command": "docker",
      "args": [
        "run", "-i", "--rm",
        "-v", "/path/to/workbooks:/data",
        "ghcr.io/psu3d0/spreadsheet-mcp:latest-full",
        "--transport", "stdio"
      ]
    }
  }
}

:latest is the read-only slim image (write/fork/recalc tools disabled); :latest-full includes the write tools and recalculation (LibreOffice-backed).

HTTP mode

spreadsheet-mcp --workspace-root /path/to/workbooks
# -> http://127.0.0.1:8079  (POST /mcp)

Configuration

Every setting is available as a CLI flag (spreadsheet-mcp --help), an environment variable, or a config file key (--config file.yaml). CLI takes precedence over the config file.

Setting any of the timeout/limit variables (TOOL_TIMEOUT_MS, MAX_RESPONSE_BYTES, MAX_PAYLOAD_BYTES, MAX_CELLS, MAX_ITEMS) to 0 disables that limit.

MCP tool surface

Read and discovery

• list_workbooks

• describe_workbook

• list_sheets

• workbook_summary

• sheet_overview

• sheet_page

• read_table

• range_values

• inspect_cells — detail-view for up to 25 individual cells with full metadata (value, formula, style, number format)

• layout_page — render a sheet range with layout semantics (column widths, borders, merges) as JSON and optionally an ASCII grid

• grid_export — export a range as a rich grid payload with per-cell values, formulas, number formats, styles, column sizes, and merges

• named_ranges

• sheet_styles

• workbook_style_summary

• close_workbook — evict a workbook from cache

Search and analysis

• find_value

• find_formula

• sheet_formula_map

• formula_trace

• scan_volatiles

• table_profile

• sheet_statistics

• get_manifest_stub

• execute_manifest — execute a SheetPort manifest with JSON inputs

Verification

• verify_workbook — compare baseline/current workbook or fork ids and report target proof plus new/resolved/preexisting errors; the summary-first proof step after recalculate

Stateful write and recalc

• fork lifecycle

• checkpoints

• edit_batch

• transform_batch

• style_batch

• grid_import — import a rich grid payload (values, formulas, styles, formats, column sizes, merges)

• apply_formula_pattern

• structure_batch

• column_size_batch

• sheet_layout_batch

• rules_batch

• define_name / update_name / delete_name — manage named ranges in a fork

• replace_in_formulas — find and replace text in formula bodies only, plain text or regex, preview or apply

• recalculate

• get_edits — list all edits applied to a fork

• get_changeset

• save_fork

• staged-change management

• screenshot_sheet

VBA inspection

• vba_project_summary

• vba_module_source

JS SDK and WASM status

spreadsheet-kit-sdk

The JS SDK is the app-facing integration layer.

It normalizes:

• method names

• input aliases

• output shapes

• typed capability errors

It is designed so an integration can target:

• MCP backends now

• WASM/session backends as they mature in embedded runtimes

Install:

npm i spreadsheet-kit-sdk

spreadsheet-kit-wasm

The Rust crate exists in this repository and provides a WASM-facing byte/session wrapper around the shared engine.

Current status:

• the crate exists and is tested in-repo

• it is not yet published as a general-purpose public package

• the npm spreadsheet-kit-wasm distribution remains planned

So the right framing today is:

• WASM is real inside the repo

• public distribution and broader packaging are still evolving

Recalc backends

Formula recalculation is pluggable.

Feature notes:

• recalc-formualizer is enabled by default

• recalc-libreoffice is available for LibreOffice-backed builds

• read and many write flows still work without recalc; only recalculate itself requires a backend

Docker images

Published at ghcr.io/psu3d0/spreadsheet-mcp:

Examples:

# Read-only
docker run -v /path/to/workbooks:/data -p 8079:8079 ghcr.io/psu3d0/spreadsheet-mcp:latest

# Write + recalc
docker run -v /path/to/workbooks:/data -p 8079:8079 ghcr.io/psu3d0/spreadsheet-mcp:latest-full

Workspace layout

spreadsheet-kit/
├── crates/
│   ├── spreadsheet-kit/        # shared engine + asp / agent-spreadsheet CLI
│   ├── spreadsheet-mcp/        # MCP server adapter
│   └── spreadsheet-kit-wasm/   # experimental WASM-facing wrapper
├── npm/
│   ├── agent-spreadsheet/      # npm CLI wrapper
│   └── spreadsheet-kit-sdk/    # JS SDK
├── docs/                       # architecture and design docs
├── benchmarks/                 # scenario budget regression harnesses
└── .github/workflows/          # CI, release, docker builds

Package roles

Architecture notes

Core ideas:

• one semantic core shared across CLI, MCP, session, and WASM-facing work

• region detection for structural awareness

• token-efficient defaults so agents do not over-read spreadsheets

• verification as a first-class feature rather than an afterthought

• workflow helpers for the common mutations that spreadsheet agents repeatedly struggle with

Token-efficient workflow reference:

Recommended progression:

1. discover workbook + sheets

2. detect regions / table-like structures

3. inspect only the exact region or cells needed

4. mutate with dry-run or session staging

5. recalculate if needed

6. verify proof and review grouped diffs

Development

# Build everything
cargo build --release

# Run formatting, lint, and tests
cargo fmt --all -- --check
cargo clippy --workspace --all-targets -- -D warnings
cargo test --workspace

Local MCP iteration:

WORKSPACE_ROOT=/path/to/workbooks ./scripts/local-docker-mcp.sh

Or point your MCP client directly at the local binary:

{
  "mcpServers": {
    "spreadsheet": {
      "command": "./target/release/spreadsheet-mcp",
      "args": ["--workspace-root", "/path/to/workbooks", "--transport", "stdio"]
    }
  }
}

Read more

• CLI package README: npm/agent-spreadsheet

• Core crate README: crates/spreadsheet-kit

• MCP crate README: crates/spreadsheet-mcp

• JS SDK README: npm/spreadsheet-kit-sdk

• WASM wrapper README: crates/spreadsheet-kit-wasm

• Packaging/versioning notes: docs/PACKAGING.md

• Heuristics and region detection: docs/HEURISTICS.md

• Recalc architecture: docs/RECALC.md

License

Apache-2.0