spreadsheet-read-mcp by PSU3D0 - MCP Server

Spreadsheet Read MCP

spreadsheet-read-mcp is a Model Context Protocol (MCP) server that lets LLM agents explore spreadsheet workbooks safely and deterministically. It focuses on high-signal, read-only insights (structure, formulas, styles, statistics) without mutating the source files. The server is optimized for XLSX first and can discover .xls/.xlsb files, while keeping the backend pluggable for future formats.

What It Does

Enumerates workbooks inside a workspace, exposing stable short IDs that are easy for an LLM to reference.
Streams sheet pages, highlights formulas, and surfaces cached values so models can inspect data slices without loading entire files.
Maps formula clusters, traces precedents/dependents with pagination-friendly summaries, and tags volatile functions.
Reports workbook metadata, sheet classifications, style usage, and named ranges to give agents a comprehensive mental model.
Provides manifest stubs and bookkeeping helpers so downstream harnesses can integrate the results quickly.

What It Is Not

No spreadsheet writing, mutation, or recalculation; everything is read-only.
No XLS macro execution, VBA inspection, or automation beyond surface metadata.
No on-the-fly format conversion; ODS and other backends will require future CAPS-enabled adapters.
Not a generic file browser — it focuses strictly on spreadsheet-aware inspection.

Quick Start

# Run directly from the repository (SSE transport at http://127.0.0.1:8079/mcp/sse)
cargo run --release -- \
  --workspace-root /path/to/workbooks \
  --cache-capacity 10

To install the binary locally:

cargo install --path spreadsheet-read-mcp
spreadsheet-read-mcp --workspace-root /path/to/workbooks

By default the server speaks MCP over Server-Sent Events (SSE). Connect an MCP-aware client to GET http://127.0.0.1:8079/mcp/sse and use the initial event payload to post JSON requests to http://127.0.0.1:8079/mcp/message. Provide --http-bind <ADDR> to choose a different address, --transport http for the streamable HTTP transport, or --transport stdio to retain the classic stdio mode.

Configuration Options

You can configure the server through CLI flags, environment variables, or a YAML/JSON config file.

CLI / Environment

Flag	Env Var	Description
`--workspace-root <DIR>`	`SPREADSHEET_MCP_WORKSPACE`	Root directory to scan for workbooks (defaults to current directory).
`--cache-capacity <N>`	`SPREADSHEET_MCP_CACHE_CAPACITY`	Maximum in-memory workbook cache size (minimum 1, default 5).
`--extensions ext1,ext2`	`SPREADSHEET_MCP_EXTENSIONS`	Allowed file extensions (defaults to `xlsx,xls,xlsb`).
`--workbook <FILE>`	`SPREADSHEET_MCP_WORKBOOK`	Lock the server to a single workbook without scanning the workspace.
`--enabled-tools tool1,tool2`	`SPREADSHEET_MCP_ENABLED_TOOLS`	Restrict execution to the named tools; others return an MCP `invalid_request`.
`--transport <sse	http	stdio>`
`--http-bind <ADDR>`	`SPREADSHEET_MCP_HTTP_BIND`	Bind address for network transports (SSE/HTTP), defaults to `127.0.0.1:8079`.
`--config <FILE>`	–	Load settings from a YAML or JSON file. CLI/env values override file entries.

Config File Example (`config.yaml`)

workspace_root: /data/spreadsheets
cache_capacity: 8
extensions: ["xlsx", "xlsb"]

Start the server with spreadsheet-read-mcp --config config.yaml.

Transports

sse (default): Serves the MCP SSE interface with GET /mcp/sse for events and POST /mcp/message for JSON payloads. Ideal for local development where clients expect the classic SSE workflow.
http: Enables the streamable HTTP transport at /mcp, which combines JSON payloads and event streams over a single upgraded connection.
stdio: Keeps compatibility with stdio-based clients. Use --transport stdio to enable it.

Tool Surface

Tool	Why It Matters
`list_workbooks`	Lists discoverable workbooks with slug + short ID so agents can choose targets without remembering long hashes.
`describe_workbook`	Returns workbook-level metadata (size, sheet count, CAPS) to gauge complexity before drilling in.
`list_sheets`	Presents sheet summaries, visibility, metrics, and tags to help prioritize inspection order.
`sheet_overview`	Offers classification, headline stats, and highlights (tables, named items) for a single sheet.
`sheet_page`	Pages through tabular data with optional formula/style payloads, enabling high-signal slices for LLM review.
`sheet_formula_map`	Groups identical formulas and aggregates ranges so the agent can spot patterns without sifting cell-by-cell.
`formula_trace`	Walks precedents/dependents recursively (with safe pagination) to explain how values propagate across sheets.
`named_ranges`	Surfaces named items, their scope, and target ranges to anchor reasoning in business terminology.
`sheet_statistics`	Captures distribution metrics, data density, and heuristics that describe how "busy" a sheet is.
`find_formula`	Searches formulas by text/regex, ideal for locating specific functions or references quickly.
`scan_volatiles`	Flags volatile functions and high-churn ranges so models can reason about recalculation risk.
`sheet_styles`	Summarizes style reuse and annotations, revealing which cells carry semantic emphasis or commentary.
`get_manifest_stub`	Emits a structured stub that downstream pipelines can drop into corpus manifests.
`close_workbook`	Explicitly evicts a workbook from the cache to free memory between exploratory sessions.

Workspace Semantics

Workbooks are discovered relative to the configured workspace root. Subdirectories are preserved; use list_workbooks filters (slug_prefix, folder, path_glob) to focus the scan.
Single-workbook mode (--workbook) skips directory traversal and indexes only the specified file, while still providing the usual short ID aliases.
XLSX files are fully parsed through umya-spreadsheet. XLS/XLSB are enumerated and validated before load; unsupported structures are reported as MCP errors instead of crashing the server.
A bounded LRU cache keeps recently accessed workbooks warm while respecting memory limits.

Development

Format / lint using standard Rust tooling (cargo fmt, cargo clippy).
Run the full test suite with cargo test from the project root; integration tests synthesize workbooks on the fly via umya-spreadsheet fixtures.

When opening pull requests, GitHub Actions will automatically run the cross-platform test + build workflow defined in .github/workflows/ci.yml and publish release binaries as artifacts.

PSU3D0/spreadsheet-read-mcp