Configuration

zenoh-mcp is configured almost entirely per-call. The only global knob is the default router endpoint.

Choosing a router

Every tool accepts an optional connect argument — a Zenoh endpoint such as tcp/192.0.2.10:7447. The endpoint is resolved in this order:

1. The tool’s connect argument, if provided.
2. The ZENOH_CONNECT environment variable.
3. The built-in default, tcp/localhost:7447.

This makes it easy to target multiple routers from one server instance: set a sensible default in ZENOH_CONNECT, and override connect per call when you need a different one.

zenoh_list_keys { }                                  → uses ZENOH_CONNECT or localhost
zenoh_list_keys { "connect": "tcp/192.0.2.20:7447" } → that router instead

Connection model

• The server always opens client-mode sessions, never peer or router mode. It attaches to the router you name and nothing else.
• Multicast scouting is disabled, so there is no LAN discovery traffic and no waiting on scout timeouts — connections to an explicit endpoint are immediate.
• Each tool call is stateless: open session → one operation → close. There is no long-lived subscription held between calls, which keeps the server safe to point at production routers.

Endpoint formats

Zenoh endpoints follow <protocol>/<address>[:port]. Common ones:

Endpoint	Meaning
tcp/localhost:7447	local router, default Zenoh port
tcp/192.0.2.10:7447	remote router by IP
tcp/[::1]:7447	IPv6 loopback

Logging

The server logs to stderr (stdout is reserved for the MCP JSON-RPC stream). Control verbosity with RUST_LOG:

RUST_LOG=zenoh_mcp=debug,zenoh=info zenoh-mcp