gridcraft/docs/mcp.md

GridCraft MCP server

gridcraft-cli mcp exposes GridCraft to AI agents over the Model Context Protocol: newline-delimited JSON-RPC 2.0 on stdin/stdout (protocol 2025-06-18; 2025-03-26 and 2024-11-05 clients are answered in their own version). Logs go to stderr.

Two backends:

Mode	Command	What it drives
Headless (default)	gridcraft-cli mcp [--in book.xlsx | --sample budget]	An in-process engine session — no window.
Remote	gridcraft-cli mcp --connect 7979	A running app started with gridcraft --control 7979 (TCP JSON lines on 127.0.0.1, authenticated with the app's token: it is read from the app's token file or GRIDCRAFT_CONTROL_TOKEN, see control-protocol.md).

Claude Code

claude mcp add gridcraft -- gridcraft-cli mcp
# or drive the desktop app you are looking at:
claude mcp add gridcraft-app -- gridcraft-cli mcp --connect 7979

JSON config (.mcp.json, Claude Desktop, other clients):

{
  "mcpServers": {
    "gridcraft": {
      "command": "gridcraft-cli",
      "args": ["mcp"]
    }
  }
}

Use "args": ["mcp", "--connect", "7979"] for the desktop app, or ["mcp", "--in", "/path/book.xlsx"] to start with a file open.

Tools

Tool	Arguments	Does
execute_command	command, params?	Runs any engine command (cell.set, home.bold, data.removeDuplicates, …).
list_commands	search?	Command ids, labels, ribbon paths, shortcuts and parameter docs.
list_windows	—	Open windows: window id, workbook (doc) id, title ("Book1", or "Book1:2" for a workbook's second window), unsaved changes, active, hidden.
inspect_workbook	—	Sheets, used ranges, tables, charts, names, selection, history.
read_range	range?, sheet?, formulas?, formatted?	Rows of values (default: the used range).
write_range	range, values (2-D)	range.setValues; strings starting with = are formulas.
set_cell / get_cell	cell, input / cell	Enter one cell / read value, formula, display text, style.
evaluate_formula	formula, cell?	Evaluates without changing the sheet. A formula that couldn't be entered in a cell (it doesn't parse, or a function gets the wrong number of arguments) is an error saying why.
select	range, active?	Sets the selection.
format_range	range, bold?, italic?, underline?, fontName?, fontSize?, fontColor?, fillColor?, numberFormat?, horizontalAlign?, wrapText?, borders?	Composes the home.* formatting commands.
insert_chart	range, type, title?, subtype?, at?	insert.chart.
create_table	range, style?, header?, name?	insert.table.
sort_range	keys, range?, header?	data.sort; keys are "B", "B desc" or {column, order}.
filter	column, range?, values?, custom?, top?, blanks?, clear?	data.filterBy (turns AutoFilter on when needed).
open_workbook / save_workbook / new_workbook	path / path? / sample?	Files (.xlsx, .csv, .tsv, .json, .html).
undo / redo	steps?	History.
screenshot	path	PNG of the window (Remote only).
list_functions	search?, category?	Worksheet functions with signatures.

Every tool that acts on a workbook (all but list_commands, list_functions, list_windows, open_workbook, new_workbook and screenshot) also takes window or doc, an id from list_windows, and acts in that window (for doc, the workbook's most recent window) without bringing it forward. Without them it acts in the active window.

Results are one text block holding pretty JSON; failures set isError: true with a readable message. Unknown tools, missing required arguments and wrong argument types are JSON-RPC -32602 errors; malformed JSON is -32700; unknown methods -32601.

Resources

• gridcraft://workbook — document.inspect of the active workbook.
• gridcraft://commands — every command with its parameter docs.
• gridcraft://functions — every worksheet function.

prompts/list returns an empty list.

Example session

→ {"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18"}}
→ {"jsonrpc":"2.0","method":"notifications/initialized"}
→ {"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"write_range","arguments":{"range":"A1","values":[["Item","Cost"],["Rent",1200],["Food",400],["Total","=SUM(B2:B3)"]]}}}
→ {"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"read_range","arguments":{"range":"B4"}}}
← {"jsonrpc":"2.0","id":3,"result":{"content":[{"type":"text","text":"{\n  \"range\": \"B4\", ... \"values\": [[1600.0]]\n}"}],"isError":false}}

Embedding

gridcraft-mcp is a library: Server::new(Box::new(Headless::new())) or Server::new(Box::new(Remote::connect(&control_addr("7979"))?)), then Server::serve(stdin, stdout) or Server::handle_line(line) -> Option<String>. Implement the Backend trait (call(method, params)) to drive another host.