What is capsule?
capsule is a MCP server by mavdol that run untrusted Python/JavaScript code in WebAssembly sandboxes. It is listed under Developer tools and has 298 GitHub stars.
| Type | Mcp server |
|---|---|
| Author | mavdol |
| Repository | mavdol/capsule |
| Popularity | 298 GitHub stars |
| Category | Developer tools |
| Security | Review before installing (72/100) |
| Rank | #328 of 4,418 MCP servers; #104 in Developer tools |
| License | Apache-2.0 |
| Last commit | 2026-10-12 |
| Runs | Locally |
| Language | Rust |
| Platforms | macOS, Windows, Linux |
Is capsule safe to install?
capsule scores 72/100 on the MCPMods security check: Review before installing. Things to review: can take actions such as send, write or deploy; executes code or shell commands. It passed 3 of 6 checks.
MCP server results come from listing signals: who publishes it, where your data goes and what it can do. The code itself is not scanned yet.
| Check | Result |
|---|---|
| Community-built server | Note |
| Runs on your machine only | Pass |
| No credentials mentioned | Pass |
| Can take actions such as send, write or deploy | Review |
| Executes code or shell commands | Review |
| Source on GitHub | Pass |
How do I install capsule?
- Find the launch command. The README says how the server starts (npx, uvx, docker or a remote URL) and which API keys it needs.
https://github.com/mavdol/capsule/tree/main/integrations/mcp-server
- Add it to Claude Code. Replace the part after -- with the command from the README. Remote servers use --transport http with a URL.
claude mcp add capsule -- <command from README> claude mcp add --transport http capsule <server-url>
- Check it connected. This lists your MCP servers and their status.
claude mcp list
Or ask Claude to set it up
Paste this into Claude Code and it installs capsule for you:
Add the "capsule" MCP server from https://github.com/mavdol/capsule/tree/main/integrations/mcp-server to Claude Code. Read its README for the launch command and any API keys I need, run claude mcp add, then check that it connects.