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Calllint

by calllintversion 0.2.1i★ –iRuns on your computer
Registry nameio.github.calllint/calllint

Install

Overview

Description from the maker (original English)

Static preflight safety gate for MCP servers — scan configs before you run them. Never executes.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

  • Connection: Runs on your computer
  • Transport: stdio
  • Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

  • Basic checks: 1 of 1 passed
  • Runs on your computer with your user’s permissions (files, network, apps).
  • The registry lists no key to fill in.

You need

  • npmNode.js installed (for the npx command)

Which app do you use?

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

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

Run this in your terminal

claude mcp add calllint -- npx -y calllint-mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

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

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "calllint": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "calllint-mcp"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 6, 2026

  • ✓ Pass

    Maker matches the repo

    The registry name was verified with the GitHub account calllint, which owns the repo

  • … Not checked yet

    Still maintained

    We have not read this repo from GitHub yet

  • … Not checked yet

    Has a licence

    We have not read this repo from GitHub yet

  • – Not applicable

    Endpoint responds

    This one runs on your computer; there is no internet endpoint

  • – Not applicable

    Sign-in with OAuth

    Runs on your computer and uses local settings instead

  • … Not checked yet

    No hidden instructions in tool descriptions

    Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

  • More stars than 0% of the other 32417 servers in this category
  • Published to the registry more recently than 72% of the other 32417 servers in this category
  • Basic checks equal to or better than 100% of the other 32417 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Calllint safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.2.1) reached the registry 14 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, FOGA node

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Spec Driven Development

by formulahendry

MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.

Runs on your computer★ 440MITUpdated 14 months ago
Install

Remote Desktop Commander

by desktop-commander

Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.

Runs in the cloud★ 211Updated yesterday
Install

FOGA node

by garyyang-finchip

A Finch OG Agent cell as an MCP server: read the world, dry-run and take ERC-8414 tenders by policy.

Computer or cloudUpdated today
Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

CallLint

Your agent can run tools faster than you can review them.

CallLint is a pre-flight risk linter for MCP and agent-tool configs. It checks the blast radius before the tool runs: what each tool can read, write, execute, connect to, send, or mutate — then returns an evidence-backed verdict (SAFE / REVIEW / BLOCK / UNKNOWN) before your agent ever loads the server.

It never executes, installs, or connects to the servers it judges.

npx calllint scan .cursor/mcp.json

Status: 1.9.2 stable CLI release. Actively hardened. Verdicts are heuristic

decision support, not a safety guarantee. Read Limitations

before relying on a verdict for a security decision.

$ npx calllint scan .cursor/mcp.json

result: BLOCK (BLOCK 1 · UNKNOWN 0 · REVIEW 0 · SAFE 0)

BLOCK helpful-notes PROMPT · SUPPLY • [BLOCKER] Model-directed instruction in tool metadata evidence: tools.save_note.description = "do not tell the user" • Package version is not pinned evidence: package = helpful-notes@latest autonomous use: deny · manual approval: required

What is CallLint?

The authority a tool configuration grants is the union of the permissions and capabilities CallLint can observe in that configuration and its supplied tool metadata. A single MCP server can add filesystem write, shell execution, network egress, or model-directed instructions to an autonomous agent — usually described only by untrusted, tool-provided metadata. CallLint inspects that static surface and tells you, with evidence, what you would be granting before you grant it; it does not claim to observe an agent's total runtime or cloud authority.

  • Deterministic — same input, same verdict. No model in the decision path.
  • Offline by default — no network unless you pass --online (advisory only).
  • Evidence-backed — every finding cites the exact config field it came from.
  • Never executes the target — it reasons about configuration, not behavior.

What it checks

CallLint runs thirteen static detectors over each server entry:

DetectorRisk symbolWhat it flags
secretEnvKeys🔐 SecretsEnv keys whose names imply credentials (tokens, keys, passwords), incl. docker inline -e KEY
broadFilesystemPath📁 FilesFilesystem roots that grant broad read/write (/, ~, home, drive roots), incl. docker bind-mount host paths
unknownRemote🌐 NetworkRemote/HTTP transports to unrecognized or unpinned hosts
promptPoisoning🧠 PromptModel-directed instructions hidden in tool names, descriptions, or schemas
hiddenInstructions🧠 PromptHidden/obfuscated content (zero-width, bidi, tag-char, HTML comments) in model-visible metadata
dangerousCommand⚙️ ExecShell-out / interpreter / package-runner commands (bash -c, npx, …)
unverifiedLocalSource⚙️ ExecLocal script/binary that is not a recognized package, pinned image, or remote
externalMutation✉️ ActionTools that send or mutate external state (email, messages, posts)
messagingSend✉️ ActionTools that send messages/email on your behalf (Slack, Twilio, SMTP, …)
oauthScope✉️ ActionOAuth scopes that are undeclared, broad, or expansive (admin, *, repo, …)
gatewayRuntime✉️ ActionLong-running gateway runtimes that proxy many downstream tools under one auth
financialAction💸 MoneyPayment / transfer / irreversible financial actions
unpinnedPackage🧩 SupplyUnpinned package specs (@latest, no version) — rug-pull surface

Findings roll up into a risk class (S0 metadata-only → S5 financial/irreversible) and an aggregate verdict per server and per config.

Drift detection (baseline / verify) records an approved risk surface and flags rug-pulls (🔁) — a previously-approved server whose risk surface later changed.

What it does not check

This list matters more than the feature list. CallLint is a *pre-flight check*, not a proof of safety.

  • It does not execute, install, or connect to servers — so it cannot observe actual runtime behavior (what a server really reads, writes, or sends).
  • It does not read or validate secret values — it inspects config *shape* (key names), never the contents of your .env or credential stores.
  • It does not analyze server source code — only the configuration and any tool metadata you provide under x-calllint.tools.
  • It does not fetch anything unless you pass --online, and online results are advisory — they never upgrade a verdict toward SAFE.
  • It does not certify third-party tools, replace human security review, or guarantee an agent is safe.
  • A clean run is necessary, not sufficient. Pair it with code review, least-privilege tokens, and runtime controls.

UNKNOWN is a real verdict: when CallLint cannot verify what a server will do, it says so and never silently upgrades UNKNOWN to SAFE.

What CallLint is — and is not
CallLint is notCallLint is
a runtime sandboxa pre-run risk linter for agent-tool configs
a secret scanner (it never reads secret values)a config-shape inspector that flags credential-shaped keys
npm audit (known package CVEs)a blast-radius check on the authority you are granting
a server source-code analyzera static config + tool-metadata analyzer
a safety certificateheuristic decision support, not a safety guarantee
a replacement for human reviewthe start of a review, with evidence attached

Install

# run without installing (recommended):

npx calllint scan ./mcp.json

or install globally:

npm install -g calllint

Requires Node.js ≥ 20. The published package is a single self-contained bundle with zero runtime dependencies. calllint on the latest tag is the current stable CLI release; @next carries release candidates and @preview older previews.

Quick start

Zero-config scanning — discover and scan all your agent configs:

# Auto-discover and scan all agents (Cursor, Claude Code, Claude Desktop, VS Code, Windsurf)

calllint scan --auto

List all discovered agent configs

calllint inventory

Scan a specific agent type

calllint scan --agent cursor calllint scan --agent vscode

Manual path scanning — scan a specific config file:

# scan a config file (auto-detects common locations if no path given)

calllint scan ./mcp.json

scan from stdin, machine-readable JSON out

cat .cursor/mcp.json | calllint scan --stdin --json

CI gate: non-zero exit per policy (BLOCK=30, UNKNOWN=20, REVIEW=10 if enabled)

calllint scan ./mcp.json --ci --no-emoji

synthesize a config for an npm package (offline) or a GitHub repo (--online)

calllint scan npm:mcp-weather@1.0.0 calllint scan github:owner/repo --online

record an approved baseline, then detect drift / rug-pulls later

calllint baseline ./mcp.json calllint verify ./mcp.json --ci

explain one server's verdict from the last scan

calllint explain filesystem

structured diagnostics for editor / agent-host integration

calllint diagnostics ./mcp.json --json

Output formats: default terminal, --compact, --json (stable schema), --sarif (GitHub Code Scanning), --markdown (PR comments / GitHub Step Summary), --html (self-contained report). The diagnostics command emits a separate editor/agent-host JSON (calllint.diagnostics.v0).

See CallLint running in CI on a deliberately risky config — calllint-demo-risky-mcp publishes one Code Scanning alert per finding on every push.

Beyond config scanning

The same engine and verdict semantics extend past MCP-config scanning to other points where an agent grants authority:

# Preflight a planned external action before the agent runs it

calllint action inspect payment.json # calllint.action.v0 descriptor calllint action inspect email-reply.json --json

Preflight a normalized agent inbox event (delegates to the action analyzer)

calllint inbox inspect gmail-reply.normalized.json

Record a scan as a local, verifiable receipt, then validate it later

calllint scan ./mcp.json --receipt # writes calllint-receipt.json calllint receipt verify calllint-receipt.json

Attach an external content-scanner report as evidence (joint Trust Packet)

calllint scan ./mcp.json --evidence skillspector-report.json

Receipts (calllint.receipt.v0) are a reporting layer derived from a scan — they prove which CallLint version produced which verdict over which input under which policy. They are not a second scanner and never re-judge a verdict. A receipt can carry an optional ed25519 signature; receipt keygen / receipt sign generate and sign one locally for development, and receipt verify checks the signature when present (offline, with --public-key). A signature proves provenance and integrity — never safety.

Trust Gateway — prepare, approve, apply, verify

Scanning tells you the blast radius; the Trust Gateway acts on it, safely. It resolves an agent-tool target to an immutable, digest-pinned identity, judges it deterministically, and emits a reversible install plan. Applying that plan is the only thing that ever writes live config: it re-validates every digest, writes atomically, verifies the result, and rolls back on failure. The gateway never executes, installs, or connects to the target it judges.

# read-only: resolve + judge a target and emit a reversible plan (touches no live config)

calllint trust prepare github:owner/repo --host claude-code --write-plan calllint trust show .calllint/plans/ .json calllint trust explain .calllint/plans/ .json

the only writer of live config — applies an approved plan, atomically and reversibly

calllint trust apply --plan .calllint/plans/ .json --approve --receipt

validate a decision receipt later (read-only; never re-judges or executes)

calllint trust verify calllint-decision-receipt.json --public-key key.pub

The gateway is a deterministic, fail-closed pipeline over six sealed digests (artifact → evidence → authority → decision/policy → install-plan → receipt). An approval binds all six at once; if any digest changes between prepare and apply, the approval is void and nothing is written. UNKNOWN never becomes SAFE, and external evidence can tighten a verdict but never set it alone. Five Tier-A hosts ship the audited apply surface — Claude Code, Cursor, Windsurf, Claude Desktop, and VS Code. See the CHANGELOG (Trust Gateway Core) and ADRs 0035–0039.

Continuous Guard — catch a rug-pull after approval

A tool you approved once can change later. calllint guard records the approved authority surface and re-decides it — silent when nothing changed, and loud the moment a previously-approved server's risk surface shifts (a rug-pull, 🔁). It adds no new verdict engine: it reuses the same deterministic drift check as baseline / verify and the same stable exit codes.

# re-assess the current authority surface vs the approved baseline (silent when unchanged)

calllint guard

install a guard hook into a host — a declarative shim that only shells out to calllint guard

calllint guard install --host git # git pre-commit hook calllint guard install --host github # GitHub Actions drift-gate workflow calllint guard status # baseline / disable / installed-hook state calllint guard disable # writes .calllint/guard.json { enabled: false }

Guard installs on seven hosts: git (pre-commit), git-pre-push, github (Actions), claude-code, copilot, gemini, and vscode. Every hook binds only to a commit / push / CI / session-start event —

Only the beginning is shown; read the rest in the repo

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