rmor

Secure web fetch MCP server for Claude Code CLI, written in Rust.

Claude Code's built-in web_fetch passes web content directly into the LLM context with no sanitisation or injection detection. This is especially dangerous in YOLO mode — a malicious page can inject instructions that hijack the agent mid-session.

rmor replaces web_fetch with a local MCP server that can go interactive when suspicious content is detected, so the user decides before anything enters Claude's context.

Current status: straight-through pass with request logging. Scanning and the interactive circuit breaker are not yet implemented — see doc/todo.md.

Requirements

• Rust toolchain (stable) — install via rustup

Installation

Build from source

git clone https://github.com/jimbarritt/rmor
cd rmor
cargo build --release

The binary lands at target/release/rmor. Copy it somewhere on your $PATH if you want:

cp target/release/rmor ~/.local/bin/rmor

Running locally

rmor communicates over stdio using the MCP protocol. You don't run it directly — Claude Code launches it as a subprocess.

Register with Claude Code

Add rmor to your Claude Code MCP config. Edit ~/.claude/claude_desktop_config.json (or ~/.claude/settings.json depending on your version):

{
  "mcpServers": {
    "rmor": {
      "command": "/path/to/rmor",
      "args": []
    }
  }
}

Replace /path/to/rmor with the full path to the binary, e.g. ~/.local/bin/rmor or /Users/you/Code/rmor/target/release/rmor.

Restart Claude Code. The web_fetch tool provided by rmor will now be available in your session.

Log file

Every HTTP request is logged to ~/.rmor/rmor.log. The directory is created automatically on first run.

tail -f ~/.rmor/rmor.log

Testing the server manually

You can exercise the MCP handshake directly over stdio:

printf '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"test","version":"0.1"}}}\n' \
  | ./target/debug/rmor 2>/dev/null

Expected output:

{"jsonrpc":"2.0","id":1,"result":{"protocolVersion":"2024-11-05","capabilities":{"tools":{}},"serverInfo":{"name":"rmcp","version":"0.16.0"},"instructions":"Secure web fetch. Logs all requests to ~/.rmor/rmor.log."}}

Development

cargo build          # debug build
cargo build --release
cargo test

Logs go to stderr during development if you set RUST_LOG:

RUST_LOG=debug cargo run

License

MIT