numbers-le-mcp

Useful? A star or rating is how other developers find it — ★ GitHub · ★ Open VSX · ★ Marketplace

What it does

Open a file, run Numbers-LE: Extract Numbers, and every numeric value in the document lands in a new editor — deduplicate and sort it from there. Works in VS Code and in VS Code–based editors like Cursor and VSCodium (installable from Open VSX).

• Data validation — pull the numbers out of a config or fixture and eyeball ranges at a glance

• Config audits — compare ports, thresholds, and limits across INI/TOML/.env files

• CSV work — extract everything, one column, or several columns into separate documents

Related MCP server: paths-le-mcp

Install

Use it from an AI agent

The same engine runs as an MCP server, so an agent can call it directly instead of you running a command.

extract_numbers(content, format?, filename?, dedupe?, maxResults?)

Returns the values in document order, each with the notation it was written in and — for JSON, source code and plain text, where the position is exact — its 1-based line and column; a parsed format (YAML, TOML, CSV, INI, dotenv) carries no position rather than a guessed one. Capped at 500 by default with meta.truncated. A format is optional — anything unrecognised is scanned as plain text rather than refused.

The server takes content and returns data — it reads no files and makes no network requests of its own. Published as numbers-le-mcp on npm and as io.github.nolindnaidoo/numbers-le in the MCP registry.

Most hosts read a JSON config. Add one entry:

{
  "mcpServers": {
    "numbers-le": {
      "command": "npx",
      "args": ["-y", "numbers-le-mcp"]
    }
  }
}

-y skips the install prompt on first run. Pin a version if you would rather not track releases — numbers-le-mcp@2.5.0.

Prefer not to go through npx on every launch? Install it once and point at the binary instead:

npm install -g numbers-le-mcp

{
  "mcpServers": {
    "numbers-le": { "command": "numbers-le-mcp" }
  }
}

It speaks MCP over stdio and needs no environment variables, no API key and no configuration of its own. To check it before wiring it into anything:

echo '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' | npx -y numbers-le-mcp

That prints the tool list and exits — if you see extract_numbers, the server works.

Supported formats

The shared policy (one heuristics module, applied to every format): only finite numbers are extracted — NaN and inf/.inf never appear in results — and a coerced string must be numeric in full: plain decimals with optional sign, decimal point, and exponent.

Python, Rust, Go, Java, Kotlin, C#, C, C++, JavaScript, TypeScript, SQL and shell are read by a numeric-literal extractor that understands hex 0xFF, binary 0b1010, octal 0o755 and legacy 0755, digit separators 1_000_000 and 1'000, and suffixes 123n, 1.5f, 10u32, 100L — and that knows u32 is a type name, not the number 32. A dialect changes an answer: 0755 is 493 in C, C++, Go and Java, and 755 in Rust, Python 3, Kotlin and C#.

Every finding carries the notation it was written in — decimal, hex, binary, octal, scientific, bigint. For anything left over you can pick a format explicitly or fall back to a plain-text scan (no grammar: v1.2.3 reads as 1.2 and 0.3).

The CLI

The same extraction runs from a terminal or a shell pipeline: a Rust CLI in crate/, sharing one corpus with the extension — crate/fixtures/ — so the two can never read a document differently. Install it from npm with npm install -g numbers-le (or run it with npx numbers-le) or from crates.io with cargo install numbers-le. Both install the same command and are held to the same output byte for byte, apart from the words a parser uses to refuse a broken document.

numbers-le .                     # every number in the tree; JSON on stdout when piped
numbers-le --values config/      # just the numbers, one per line
numbers-le mcp                   # the same extraction over MCP on stdio

# the point of the whole thing:
numbers-le --values --dedupe src/ | sort -n > after.txt
diff before.txt after.txt        # what constants moved this release

Install it from npm (numbers-le) or from crates.io (numbers-le). Both install the same numbers-le command.

npm install -g numbers-le   # or run it once: npx numbers-le
cargo install numbers-le

Somebody has to verify that the rate in the code is the rate in the specification. A tax percentage, a retention window, a rounding boundary. In a regulated setting that check is a deliverable, and the person doing it usually has no checkout and never has the editor open.

Numbers are printed exactly as JavaScript prints them — 1e+21, not Rust's 1000000000000000000000. This tool's whole output is numbers as text, so the rendering is the contract, and the corpus pins it.

Exit codes follow grep — 0 numbers found, 1 none found, 2 the question was malformed.

Commands

No command is bound to a key by default. Give any of them one under Keyboard Shortcuts in the editor.

Settings

Languages

Twelve languages besides English:

German · Spanish · French · Indonesian · Italian · Japanese · Korean · Portuguese (Brazil) · Russian · Ukrainian · Vietnamese · Chinese (Simplified)

Both halves are covered — the manifest (command titles, setting names and descriptions) and everything shown while the extension runs (notifications, the status bar, quick-picks and prompts). The extension follows VS Code's display language, so it matches whatever the editor is already set to; no setting of its own.

Privacy & security

• No network access. The extension never sends data anywhere. The telemetryEnabled setting only writes events to a local Output Channel you can inspect (Numbers-LE).

• The MCP server holds the same line. It takes content as an argument and returns data: no filesystem access, no network calls, no telemetry. Your agent already has file-read tools, so duplicating them inside the server would add a path-traversal surface for no capability. check:mcp-bundle fails the build if the server ever imports something that could reach either.

• Error notifications redact home directories and credential-shaped fragments.

• One rating prompt, at most twice. On the 3rd successful use the extension asks once whether you would rate it, and once more on the 20th if you chose Later or dismissed it. Don't Ask Again ends it. Setting notificationsLevel to important or silent yourself turns it off. The counts are kept in VS Code's extension storage and nothing is sent anywhere; Rate opens the listing you installed from — the VS Code Marketplace or Open VSX — in your browser.

Documentation

Performance

Median of 7 runs after warmup, on Apple M5 Pro, 24 GB RAM, Node 24.3.0. Inputs are generated by scripts/benchmark.ts rather than checked in, so the sizes above are exactly what was measured. Reproduce with bun run benchmark.

These are machine-specific and are not asserted in CI — a benchmark that gates a build only tells you how busy the runner was.

Testing

526 test cases across 37 files, plus an integration suite that runs in a real VS Code extension host and an end-to-end test that installs the built .vsix into a clean profile.

Generated from a real run — coverage/coverage-summary.json and coverage/test-results.json — by scripts/coverage-readme.js, and bun run coverage:readme:check says whether it has drifted since. Reproduce with bun run test:coverage, and the case count is the one vitest prints.

More from the LE family

Sixteen single-purpose tools for the work in front of every model. Each ships a Rust CLI and an MCP server. One page: letools.dev

Get it out

• String-LE — Extract every string in a codebase, so a person can read them

• Numbers-LE — Extract every hardcoded number in a codebase, so a person can check them

• Units-LE — Extract every quantity with its unit, normalized, and refuse the ambiguous ones by name

• Dates-LE — Extract every date and timestamp, and the exact instant each one resolves to

• IDs-LE — Extract every UUID, ULID, NanoID, ObjectId and Snowflake, and decode the time inside

• IPs-LE — Extract every IP address, CIDR block and MAC, normalized and classified by scope

• URLs-LE — Extract every URL in a codebase, with its protocol and exact position

• Paths-LE — Extract every file path in a codebase, and say whether it still points at anything

• Colors-LE — Extract every color in a codebase, and say which ones are not in your palette

Check it

• Regex-LE — Find every regex in a codebase, and report which can be driven into catastrophic backtracking

• Versions-LE — Find where one dependency is constrained differently across a repository's manifests

• i18n-LE — Identify the i18n library a project uses, then audit its catalogs by that library's rules

• Scrape-LE — Check whether a page is scrapeable before the scraper is written, and say when it cannot tell

Guard it

• Secrets-LE — Find hardcoded credentials in a codebase, and never print one into the report

• EnvSync-LE — Compare the dotenv files in a tree, and say which keys are missing from which

• Unicode-LE — Find the Unicode that hides meaning — bidi controls, invisibles, homoglyphs, mixed scripts

Each stands on its own: no shared crate, no published core. Where two of them agree, it is because the same answer was right twice.

Contact — nolindnaidoo.com · GitHub · LinkedIn

Also by nolindnaidoo

Rust — pixelcoords and pixelactions are one loop: pixelcoords answers where, pixelactions acts there. Their own tools, their own voice — not part of the LE family.

• pixelcoords — Freeze your screen, mark regions, get pixel-exact coordinates and crops pixelcoords.dev · crates.io · docs.rs

• pixelactions — Consume human-verified coordinates, perform the interaction, confirm it landed pixelactions.dev · crates.io · docs.rs

License

MIT © nolindnaidoo