Arcjet Plugin for AI Coding Agents

Arcjet is the runtime security platform that ships with your code. Enforce budgets, stop prompt injection, detect bots, and protect personal information with Arcjet's AI security building blocks.

The Arcjet plugin turns any supported AI coding agent into a security expert. It pre-loads agents with knowledge of the Arcjet security platform and automatically injects the right guidance based on what you're working on — framework-specific SDK patterns, protection rules, and best practices.

• MCP integration — connects to the Arcjet MCP Server for traffic analysis, request inspection, IP investigation, and remote rule management
• CLI integration — invokes the Arcjet CLI for authentication, site/key setup, live request streaming, and remote rule management
• Security-aware coding rules — framework-specific guidance activates automatically when you work in route handlers, API endpoints, and AI/LLM code
• Skills — task-oriented workflows sourced from arcjet/skills for adding protection to HTTP routes and non-HTTP code paths
• Security analyst agent — investigates threats, analyzes traffic, and manages rules via MCP

Installation

npx plugins add arcjet/arcjet-plugin

That's it. The plugin activates automatically — security guidance appears when you're working in route handlers, API endpoints, and AI/LLM code.

You can also point your agent at the agent get started documentation.

Arcjet CLI

The plugin invokes the Arcjet CLI for authentication, site management, and live request streaming. Install it via any of:

1. npx -y @arcjet/cli@latest <command> — no install required, works on macOS, Linux, and Windows
2. brew install arcjet — Homebrew tap
3. curl -sSfL https://arcjet.com/cli/install.sh | bash — install script
4. GitHub Releases archive — for internal redistribution and air-gapped environments

How It Works

After installing, guidance activates automatically. The plugin detects what you're working on and injects Arcjet expertise. Just use your AI agent as you normally would.

Skills

The plugin's skills are sourced from arcjet/skills, the canonical agent skills surface for Arcjet.

Skill	Purpose
/arcjet:add-request-protection	Add Arcjet protection to any HTTP route or endpoint — detects framework, sets up client, applies rules. Includes AI/LLM endpoint guidance (chat, completion).
/arcjet:add-guard-protection	Add Arcjet Guard to non-HTTP code paths — AI agent tool calls, MCP tool handlers, background jobs/workers

Deprecated aliases

The previous skill names are kept as deprecation aliases. Invoking them tells the user the new name and then proceeds with the canonical workflow — existing prompts, prompts in saved transcripts, and project-local references continue to work.

Deprecated alias	Replacement
/arcjet:protect-route	/arcjet:add-request-protection
/arcjet:add-ai-protection	/arcjet:add-request-protection (HTTP endpoints) or /arcjet:add-guard-protection (non-HTTP code)

Rules (auto-activated)

Rules provide passive guidance that activates when you work in matching files:

Rule	Activates on	Guidance
SDK patterns	**/lib/arcjet*, **/arcjet*	Single instance, protect() in handlers, withRule(), decision handling
Next.js	app/**/route.ts, app/**/page.tsx, pages/api/**	Correct imports, route handlers vs pages vs server components, no middleware
Express/Node	**/server.ts, **/routes/**	Correct adapter packages, no app.use() middleware, proxy config
Python	**/*.py, pyproject.toml	Snake_case API, enum values, async vs sync clients
AI apps	**/chat/**, **/api/chat*, **/api/completion*	Layered protection, token budgets, PII blocking, prompt injection
CLI	**/lib/arcjet*, **/arcjet*, **/.env*	When to use the CLI vs MCP, npx -y @arcjet/cli@latest invocation, agent flags

MCP Tools

When connected, your agent can use the Arcjet MCP server to:

• Inspect requests and explain allow/deny decisions
• Analyze traffic patterns and detect anomalies
• Investigate suspicious IPs (geolocation, threat intelligence)
• Create, test, and promote remote rules without code changes
• Generate security briefings

The MCP server connects automatically via OAuth when the plugin is installed. You can also connect it manually from https://api.arcjet.com/mcp

CLI

The plugin uses the Arcjet CLI for capabilities that benefit from a real terminal session:

• Authentication and site/key setup — arcjet auth login, arcjet teams list, arcjet sites list/create/get-key. The CLI is the primary way to bootstrap a new project's ARCJET_KEY.
• Live request streaming — arcjet watch --site-id <id> is invoked by the security analyst agent during active incident response, when polling list-requests over MCP would be too coarse.
• Remote rule management — arcjet rules create/list/promote/update/delete for managing rules without code changes or redeployment.

No install is required. Commands are invoked as npx -y @arcjet/cli@latest <command>, which works on macOS, Linux, and Windows. If a local arcjet binary is on PATH (Homebrew, install script, GitHub Releases archive), the plugin uses it directly. CLI authentication uses the same browser-based device flow as gh auth login or vercel login.

Read-side analysis and rule inspection over a structured tool interface remain available on the MCP server.

Security Analyst Agent

The security analyst agent uses MCP tools for monitoring and incident response:

• Traffic analysis and threat detection
• Remote rule management (DRY_RUN -> verify -> LIVE)
• IP investigation and blocking recommendations
• Structured security reports with prioritized action items

Frameworks Supported

Arcjet provides SDKs for:

JavaScript/TypeScript: Next.js, Express, Node.js, Fastify, NestJS, SvelteKit, Remix, React Router, Astro, Nuxt, Hono, Bun, Deno

Python: FastAPI, Flask

Prerequisites

• Arcjet account
• An AI coding tool

Links

• Documentation
• AI agent guide
• Bot list
• Pricing