Architecture

How it works

The AE MCP bridges Claude and After Effects using a lightweight server that translates AI intent into ExtendScript commands.

The MCP architecture

MCP (Model Context Protocol) is an open standard that lets AI assistants call external tools. Synthetic implements an MCP server that exposes 220+ After Effects operations as callable tools — Claude picks the right ones automatically based on your instructions.

Data flow

Claude (or MCP client)

──── MCP call ────▶

AE MCP Server

▼ generates JSX script

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──── ExtendScript ────▶

Adobe After Effects

▼ returns JSON result

Claude (or MCP client)

◀─── JSON result ────

AE MCP Server

The full round-trip — from Claude calling a tool to After Effects executing it and returning data — typically takes under 1 second for simple operations.

What is ExtendScript?

ExtendScript is Adobe's scripting language for Creative Cloud applications. It's a JavaScript dialect (ES3-level) that has direct access to the After Effects object model — compositions, layers, properties, render queues and everything else.

Adobe has supported ExtendScript in After Effects since CS3 (2007). Every version from CS6 through the latest 2026 release ships with the ExtendScript engine built in, which is why the AE MCP works across all of those versions with zero extra installs.

Why ExtendScript and not CEP or UXP?

Approach	Versions	Requires install
ExtendScript (used by Synthetic)	CS6 – 2026+	No — built in
CEP panel	CC 2015 – 2024	Yes — panel must be installed
UXP plugin	2022+	Yes — plugin must be installed

Because ExtendScript is built into After Effects, there's nothing to install inside AE. Just open After Effects and it's ready — the MCP server handles the rest from outside.

How the MCP server sends scripts to AE

When Claude calls a tool (for example create_comp), the MCP server:

Validates the input parameters against the tool's schema.
Generates a JSX script string containing the corresponding ExtendScript logic.
Sends the script to After Effects via the doScript file-based IPC mechanism (writing a temporary .jsx file and signaling AE to execute it).
Reads the JSON response that AE writes back to a temp file.
Returns the parsed result to Claude as the tool's output.

After Effects must be open and not blocked by a modal dialog for the MCP to communicate with it. If AE shows a "save changes?" prompt or any blocking dialog, tool calls will time out.

Security model

The MCP server runs locally on your machine — no data is sent to Synthetic's servers at runtime. Your project files, layer names, and composition data never leave your computer. The only network call is a one-time license validation against api.synthetic.com.ar when the server starts.

Overview Installation