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.

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

Tool	Purpose
ae_connection_status	Bridge/app status and capabilities
ae_project_info	Project, selection, active item, render queue metadata
ae_project_items	Search/list project tree with stable item IDs
ae_project_save	Save or Save As
ae_import_file	Import footage, projects, or sequences
ae_comp_list, ae_comp_get	Discover and inspect compositions
ae_comp_create, ae_comp_update	Create/edit composition settings
ae_layer_list	Inspect layers and top-level property groups
ae_layer_create_text, ae_layer_create_solid	Create generated layers
ae_layer_add_item	Add footage/precomps to a comp
ae_layer_update, ae_layer_duplicate, ae_layer_delete	Edit layer state and ordering
ae_property_get, ae_property_set	Read/write any value property
ae_property_keyframes	Set keyframes and interpolation
ae_property_expression	Set/disable expressions and return expression errors
ae_render_queue, ae_render_add, ae_render_start	Render queue automation
ae_batch	Up to 100 operations in a single undo group
ae_execute_script	Optional raw ExtendScript; disabled by default

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

Environment variable	Default	Description
MCP_AE_HOST	127.0.0.1	Bridge bind address; non-loopback refused
MCP_AE_PORT	19728	Bridge port
MCP_AE_TOKEN	generated	Shared bridge token
MCP_AE_TIMEOUT_MS	30000	Per-command timeout
MCP_AE_CONFIG_PATH	~/.after-effects-mcp/config.json	Shared config location
MCP_AE_ALLOW_RAW_SCRIPT	0	Set to 1 to register raw scripting tool
MCP_AE_ALLOW_REMOTE	0	Explicitly allow non-loopback binding (not recommended)

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.