mcp-server · wasmagent — Claude Code MCP server: what it does, how to install
Moves tool calls into a WASM sandbox powered by QuickJS. It reduces context token usage by presenting just docs_search and execute_code to the model.
claude mcp add mcp-server -- npx -y @wasmagent/mcp-serverWhat mcp-server does
The server packages tool collections behind a minimal two-method surface. Instead of serializing dozens of full schemas into the prompt, the host model sees only search and execution endpoints. The model then writes a small script to dispatch whichever downstream methods it needs. Under 30 downstream utilities, initial prompt token overhead drops to 13.6%.
Execution takes place inside an isolated WebAssembly QuickJS kernel. A CapabilityManifest controls access boundaries: cpuMs limits, memoryLimitBytes caps, plus strict allowedHosts and allowedPaths entries. Network requests to unapproved destinations fail immediately.
This project is in beta. Launching the zero-config binary via npx provides an empty inspection server with no tools attached. Practical deployments require a custom Node entrypoint configuring ToolRegistry.
What it helps with
- shrink prompt token overhead for large tool registries
- isolate model-generated code in a WebAssembly sandbox
- enforce strict network and disk permissions with a manifest
- host an MCP agent across stdio or edge HTTP runtimes
Example prompts for the agent
- Execute the data transformation inside execute_code with no network access
- Look up registered utilities using docs_search before running the script
- Run this calculation under a 5000ms CPU execution cap
How to install mcp-server
Platform CLI
claude mcp add mcp-server -- npx -y @wasmagent/mcp-serverPlatform CLI
codex mcp add mcp-server -- npx -y @wasmagent/mcp-serverConfig file
{
"mcpServers": {
"mcp-server": {
"command": "npx",
"args": [
"-y",
"@wasmagent/mcp-server"
]
}
}
}Config file
{
"servers": {
"mcp-server": {
"type": "stdio",
"command": "npx",
"args": [
"-y",
"@wasmagent/mcp-server"
]
}
}
}Platform CLI
gemini mcp add mcp-server npx -y @wasmagent/mcp-serverStep by step, with commands for each platform: How to add an MCP server to Claude Code, Codex, Cursor, VS Code, Gemini CLI and more
Questions about mcp-server
How to install mcp-server in Claude Code?
Run claude mcp add mcp-server -- npx -y @wasmagent/mcp-server. This command attaches the server using the stdio transport.
What is the purpose of code-mode?
It replaces heavy tool schemas with just docs_search and execute_code. The assistant inspects tool docs and runs code locally, preserving context budget.
How does the server enforce security boundaries?
The runtime checks CapabilityManifest inside the QuickJS environment. Any script attempting network calls outside allowedHosts triggers a runtime exception.
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