After Effects MCP

A production-grade Model Context Protocol connector for Adobe After Effects. It gives MCP clients structured, validated control over projects, compositions, layers, properties, expressions, keyframes, imports, and the render queue—without exposing arbitrary scripting by default.

Architecture

MCP client ──stdio──> TypeScript MCP server ──authenticated localhost WebSocket──> CEP panel ──evalScript──> After Effects

• MCP server: Node.js 20+, official MCP SDK, Zod validation, stdio transport.

• Local bridge: loopback-only WebSocket, 256-bit shared token, request IDs, timeouts, heartbeat, one active AE session.

• CEP extension: reconnecting panel with serialized command execution and visible activity.

• Host engine: ES3-compatible ExtendScript, stable item IDs, match-name property paths, structured errors, undo groups, atomic batches.

No cloud service is involved. Project data and commands remain on the local computer.

Related MCP server: ae-mcp

Features completed

• 24 MCP tools covering connection, project discovery/save/import, compositions, layers, properties, expressions, keyframes, batching, and rendering.

• Read-only/idempotent/destructive MCP annotations.

• aftereffects://status and aftereffects://guide MCP resources.

• Automatic shared config at ~/.after-effects-mcp/config.json with owner-only permissions.

• Input limits, authenticated local transport, malformed-message handling, command timeouts, and raw scripting opt-in.

• Adobe match-name paths for locale-independent property targeting.

• One After Effects undo step per mutation; one undo step for an entire ae_batch.

• macOS/Windows CEP installer script and distributable ZIP packaging.

• Unit, protocol integration, and adversarial security test suites.

Requirements

• Adobe After Effects 2020 (17.0) or newer.

• Node.js 20 or newer.

• An MCP client such as Claude Desktop, Claude Code, Cursor, or another stdio MCP host.

Install

npm install
npm run build
npm run install:extension

The extension is unsigned. Enable CEP debug mode if Window → Extensions → After Effects MCP Bridge does not appear, then restart After Effects:

macOS

defaults write com.adobe.CSXS.12 PlayerDebugMode 1
# Repeat with CSXS.11 or CSXS.10 when required by your Adobe version.

Windows (PowerShell)

reg add HKCU\Software\Adobe\CSXS.12 /v PlayerDebugMode /t REG_SZ /d 1 /f

Open Window → Extensions → After Effects MCP Bridge and keep the panel open. It reconnects automatically whenever the MCP server starts.

MCP client configuration

Build output is dist/src/server.js. Add the following to your client's MCP configuration, replacing the absolute path:

{
  "mcpServers": {
    "after-effects": {
      "command": "node",
      "args": ["/absolute/path/to/after-effects-mcp/dist/src/server.js"]
    }
  }
}

The after-effects-mcp binary is also available when the package is installed globally or linked with npm link.

Tool reference

Property path example:

["ADBE Transform Group", "ADBE Position"]

Prefer Adobe match names (ADBE ...) over display names so automation works across localized After Effects installations.

Recommended workflow

1. Call ae_connection_status.

2. Discover IDs with ae_project_items or ae_comp_list.

3. Read the target comp/layers/properties before writing.

4. Use ae_batch for related edits.

5. Inspect results, then save explicitly.

Configuration

If a custom config path is used, launch the CEP host with the same MCP_AE_CONFIG_PATH; the standard shared path needs no setup.

Security

• The server binds to loopback only unless two explicit overrides are provided.

• WebSocket upgrades require a constant-time verified 256-bit token.

• Raw ExtendScript is absent from the MCP tool list unless explicitly enabled.

• Curated tools use strict schemas and bounded arrays/strings.

• The CEP panel accepts commands only from its authenticated server connection.

• Rendering and layer deletion are marked destructive for compatible MCP clients.

Treat raw scripting as equivalent to running code under your After Effects user account.

Development and testing

npm run typecheck
npm run lint
npm run test:unit          # round 1
npm run test:integration   # round 2
npm run test:adversarial   # round 3
npm run build
npm run package:extension

npm run verify runs the complete validation pipeline. The ZIP is emitted at release/after-effects-mcp-cep.zip.

Entry points

• MCP executable: dist/src/server.js (stdio; no HTTP URI)

• Bridge WebSocket: ws://127.0.0.1:19728/bridge?token=…

• Local health check: http://127.0.0.1:19728/health

• CEP panel menu: Window → Extensions → After Effects MCP Bridge

Data/storage

No database is used. The only persistent data is the local bridge config file. After Effects project mutations are applied through Adobe's scripting API and remain undoable until the project is saved/closed.

Not implemented / platform constraints

• A signed ZXP installer is not included; signing requires a publisher certificate.

• Live end-to-end execution inside a licensed After Effects GUI cannot run in headless CI. The mock AE bridge validates protocol behavior; host-script execution should also be smoke-tested in each supported AE release.

• Dynamic Graph, Essential Graphics, Mocha, and third-party plug-in-specific APIs are reachable through property paths or optional raw scripting but do not have dedicated tools yet.

Recommended next steps

1. Sign the CEP package for managed enterprise distribution.

2. Add AE-version matrix smoke tests on dedicated macOS/Windows workstations.

3. Add dedicated tools for masks, effects, markers, cameras/lights, and Essential Graphics based on production needs.

Deployment status

This is a local desktop connector, not a Cloudflare/web deployment. Version 1.0.0 is buildable and packageable from the repository.