MCPB bundle (.mcpb)

#How MCPB bundles work

The bundle holds the server's code, its dependencies and a manifest.json that describes it. The desktop app reads the manifest, shows an install prompt, and sets the server up without a hand-edited configuration file. The manifest is the only part of the format this page describes.

#Why it matters for AI agents

Setup is where many people stop. Without a bundle, a user has to find the right config file, paste a command and restart the app. A bundle removes those steps for people who do not write code. The install prompt is still a trust decision, because the bundled server runs on your computer. Install only bundles from sources you trust.

#Wield and MCPB bundles

Claude Desktop users can install wield-mcp from a one-click bundle. Download wield.mcpb from wield.run/install and double-click it. Claude Desktop opens and asks to install Wield. The API key field is optional, so leave it empty for the free public recipes. The bridge is set up the first time Wield starts, and the bundle changes nothing else on your computer. You still add the Wield browser extension separately.

#Related terms

• MCP server: the program that a bundle installs.
• MCP client: the app that runs the installed server.
• stdio transport: how a local bundled server talks to its client.

#FAQ

#What is the difference between .mcpb and .dxt?

The format was renamed from DXT to MCPB. The file extension changed from .dxt to .mcpb. Current documentation and tools use the new name.

#How do I install a .mcpb file?

In Claude Desktop, double-click the file. Claude Desktop opens and asks you to install it. If the bundle has optional fields, such as Wield's API key, fill them in only when you need them. Confirm the install only for bundles from sources you trust.