SFMC Language Service for VS Code

A Visual Studio Code extension providing comprehensive language support for Salesforce Marketing Cloud — AMPscript, SSJS (Server-Side JavaScript), and GTL (Guide Template Language).

Features

Syntax Highlighting

• AMPscript block syntax (%%[ ... ]%%)
• Inline AMPscript expressions (%%= ... =%%)
• <script runat="server" language="ampscript"> blocks (flexible attribute order, single/double quotes)
• Variables (@name), system variables (@@ExecCtx), keywords, operators, strings, comments, function calls
• Personalization strings (%%FirstName%%, %%emailaddr%%)
• Guide Template Language (GTL) expressions ({{Name}}, {{Lookup(...)}})
• Content syndication patterns (%%HTTPGet "url"%%)

Auto-Completion

• 147 AMPscript functions with snippet-style parameter placeholders, organized across 15 categories (Data Extension, HTTP, Content, Encryption, Math, String, Date/Time, Utility, SOAP API, Salesforce, Dynamics CRM, MobileConnect, Social, Einstein, and more)
• 16 keywords with contextual snippets (var, set, if/then/elseif/else/endif, for/to/downto/do/next, and/or/not, true/false)
• 80+ system personalization strings with descriptions (subscriber identity, email/job metadata, dates, sender info, URLs, MobileConnect demographics, GroupConnect, execution context)
• File-scoped variable suggestions extracted from the current document
• Context-aware — completions only appear inside AMPscript regions

Hover / IntelliSense

• Typed function signatures with parameter documentation
• Required/optional parameter markers
• Return type information
• Usage examples
• Keyword and personalization string documentation

Signature Help

• Parameter hints while typing function arguments
• Active parameter highlighting as you type commas

Diagnostics

• Delimiter matching: Unmatched %%[/]%% and %%=/=%% pairs (both directions)
• Nesting-aware control flow: Stack-based IF/ENDIF and FOR/NEXT validation with line-level error locations
• Unknown function detection: Flags function calls not in the AMPscript catalog
• Best-practice hints: Informational warnings for bare subscriber attribute access without AttributeValue() wrapping

SSJS (Server-Side JavaScript)

• Auto-completions for Platform.Function.*, Platform.Variable.*, Platform.Response.*, Platform.Request.* methods
• Core library objects with method listings (DataExtension, Subscriber, TriggeredSend, etc.)
• WSProxy method completions
• Hover documentation for SSJS globals, Platform functions, and Core library objects
• Diagnostics: Missing Platform.Load("core", "1") detection, ES6+ syntax warnings

GTL (Guide Template Language)

• Context-aware completions inside {{ }} expressions — AMPscript functions, variables, and personalization strings
• GTL snippets for common patterns

Status Bar

A compact sfmc entry appears in the VS Code status bar (bottom-right) as soon as the extension activates:

• Spinner while the language server is starting up.
• Check mark once the server is running and ready.
• Error icon if the server stops or fails.
• Click to open the language server output channel.
• Hover for a tooltip with a Show Output link, live server status, active trace level (if enabled), and a quick Settings link to jump directly to the extension settings.

Model Context Protocol (MCP) for AI assistants

This extension registers the mcp-server-sfmc MCP server with VS Code so GitHub Copilot agent mode (and other MCP-aware chat flows) can discover SFMC tooling automatically — validation and lookups for AMPscript and SSJS, diff-aware review, fix suggestions, catalogs as resources, and guided prompts. You do not need a separate npm install or a manual .vscode/mcp.json entry for that discovery; the server is still loaded via npx when the tool runs.

Finding this extension vs. the MCP Server Gallery in VS Code

• In the Extensions view, @contribute:mcp filters extensions that contribute MCP server definitions. This extension appears there because it declares that contribution and registers mcp-server-sfmc.
• The @mcp filter opens the MCP Server Gallery, which is backed by the curated GitHub MCP Registry (not the full Marketplace catalog). Publishing the VS Code extension does not add the server to that gallery. The npm package mcp-server-sfmc is registered as io.github.JoernBerkefeld/mcp-server-sfmc (see mcp-server-sfmc mcpName / server.json); after a release, metadata is published to the MCP Registry via mcp-publisher (locally or from CI). Quickstart: Publish an MCP Server to the MCP Registry. Ensure chat.mcp.gallery.enabled is on if the gallery does not appear.

Requirements: VS Code 1.101 or newer (see engines in this extension’s package.json). Older versions can add the server manually as described in the mcp-server-sfmc README (also covers Cursor, Claude Desktop, Windsurf, and global or local installs).

Snippets

AMPscript snippets (36 built-in):

SSJS snippets (18 built-in):

GTL snippets (8 built-in):

File Types

This extension activates for:

• *.ampscript, *.amp -- AMPscript files
• *.ssjs -- Server-Side JavaScript files

Installation

Option 1: Install from VSIX

1. Build and package:

   npm install
   npm run compile
   npm run package
   

2. In VS Code: Extensions > ... > Install from VSIX... > select the generated .vsix file

Option 2: Run in Extension Development Host

1. Open the vscode-sfmc-language folder in VS Code
2. Run npm install and npm run compile
3. Press F5 and choose Launch Client
4. Open a .ampscript or .amp file in the Extension Development Host

Configuration

Architecture

vscode-sfmc-language/
├── client/              Language client (VS Code extension host)
│   ├── src/extension.ts   Starts the language server over IPC
│   └── src/test/          Integration tests (completion, diagnostics)
├── server/              Language server (Node.js LSP)
│   ├── src/server.ts        Completions, hover, signature help, diagnostics
│   ├── src/ampscriptData.ts AMPscript function catalog, keywords, personalization strings
│   └── src/ssjsData.ts     SSJS Platform functions, Core library objects, WSProxy
├── syntaxes/            TextMate grammars for syntax highlighting
│   ├── ampscript.tmLanguage.json   AMPscript + GTL grammar
│   └── ssjs.tmLanguage.json        SSJS grammar (extends JavaScript)
├── snippets/            VS Code snippet definitions
│   ├── ampscript.snippets.json     AMPscript snippets
│   ├── ssjs.snippets.json          SSJS snippets
│   └── gtl.snippets.json           GTL snippets
├── language-configuration.json      AMPscript bracket/comment/folding config
├── ssjs-language-configuration.json SSJS bracket/comment/folding config
└── package.json         Extension manifest

Development

npm install          # Install root + client + server dependencies
npm run compile      # TypeScript compilation (type-checked)
npm run watch        # Watch mode for development
npm test             # Run integration tests in VS Code instance
npm run lint         # ESLint
npm run package      # Package as .vsix

The extension uses esbuild for production bundling (vscode:prepublish), reducing load time and VSIX size.

Troubleshooting

Cannot find module 'undici-types'

npm install
npm run compile

Notes

• AMPscript function metadata is sourced from the ampscript-data shared package.
• SSJS function metadata is sourced from the ssjs-data shared package.
• This extension provides editing support for SFMC languages — it does not execute AMPscript or SSJS code.