The fastest way to lose a non-technical user is to ask them to edit a JSON config and install Node dependencies just to add one MCP server. Desktop Extensions fix that: a .mcpb bundle packs an entire MCP server — code and every dependency — into a single file you install with one click. No terminal, no config file, no dependency conflicts. Here's how the format works and when to use it.
What an .mcpb bundle is
Think of it like a Chrome extension (.crx) or a VS Code extension (.vsix), but for local MCP servers. The bundle contains the server plus everything it needs to run, so installing it is a single action instead of a multi-step setup. The host app reads the bundle, wires the server into your client, and it's available — no hand-editing the mcpServers block, no npx/uvx command to get exactly right, no "works on my machine" dependency drift. Anthropic open-sourced the bundle specification and toolchain, so it isn't Claude-only; other desktop apps can implement support too.
DXT vs .mcpb — the naming
If you've read older guides you'll see DXT (Desktop Extensions). That's the legacy name. In late 2025 Anthropic renamed the packaging to MCP Bundle, with the .mcpb extension replacing the earlier .dxt. Existing .dxt files generally still work, but new bundles use .mcpb, and that's the name to standardise on. Same idea, current label — don't let the two terms confuse you into thinking they're different systems.
When to use a bundle vs editing the config
Reach for an .mcpb bundle when you're distributing a server to people who shouldn't have to touch a config file — teammates, clients, anyone non-technical. One file, one click, done. Stick with hand-editing the config file when you're a developer iterating on a local server, wiring up several servers at once, or need fine control over arguments and environment variables. The two aren't rivals: bundles are the distribution format, the config is the power-user surface. For the manual path, see install MCP in Claude Desktop.
The trade-offs to keep in mind
Convenience cuts both ways. A one-click installer hides what the server actually does, so the vetting that matters for any MCP server matters more for a bundle — you're trusting whatever's packed inside. Prefer bundles from sources you can verify, and stay alert to the same supply-chain risks that hit packages everywhere, including rug pulls and malicious servers. A bundle is a great experience and a real attack surface at the same time.
Going further
For the bigger picture on packaged, in-client experiences — the rendered-UI cousin of bundles — read what are MCP Apps. New to setup entirely? Start with what is an MCP server and the Claude Code MCP setup guide, then browse best MCP servers for Claude Desktop or grab a loadout.