MCP Inspector

The MCP Inspector is the official visual + CLI tool for testing and debugging MCP servers. It's the fastest way to poke at this server's tool catalog and prompt library without wiring up a full AI client. Nothing to install — it runs via bunx (or npx).

Quick start (UI)Copy Anchor Link

# Dev server (loads .env automatically via Bun), opens the web UI:
bun run inspect

# Or against the bundled build in dist/:
bun run inspect:built

# Or use the committed config (lets you pick a server in the UI):
bun run inspect:config

This launches:

• the Inspector UI at http://localhost:6274 (auto-opens, token pre-filled), and
• a local proxy on port 6277.

In the UI: click Connect, then open Tools → List Tools to browse the catalog, pick one (e.g. list_interfaces), fill its arguments, and Run. Prompts → List Prompts shows the 9 guided workflows. Set the Logging level to see the per-call [device] Executing … messages this server emits.

The proxy mints a session auth token at startup and the browser opens with it pre-filled. To pin it: MCP_PROXY_AUTH_TOKEN=$(openssl rand -hex 32) bun run inspect. Override ports with CLIENT_PORT / SERVER_PORT. Avoid DANGEROUSLY_OMIT_AUTH=true.

Passing connection detailsCopy Anchor Link

The dev scripts run bun run src/cli.ts serve, and Bun auto-loads .env, so the simplest path is to put your credentials in .env (copy .env.example). To set them inline instead, use the Inspector's -e flag:

bunx @modelcontextprotocol/inspector \
  -e MIKROTIK_HOST=192.168.88.1 -e MIKROTIK_USERNAME=admin -e MIKROTIK_PASSWORD=•••• \
  bun run src/cli.ts serve

The committed mcp-inspector.config.json holds named entries you can edit (mikrotik, mikrotik-built, mikrotik-http) and select with --server.

CLI mode (scriptable / CI)Copy Anchor Link

--cli runs a single request and prints JSON — great for smoke tests:

# List every tool
bunx @modelcontextprotocol/inspector --cli bun run src/cli.ts serve --method tools/list

# List prompts
bunx @modelcontextprotocol/inspector --cli bun run src/cli.ts serve --method prompts/list

# Call a tool (connection-free — lists configured devices)
bunx @modelcontextprotocol/inspector --cli bun run src/cli.ts serve \
  --method tools/call --tool-name list_mikrotik_devices

# Call a tool that hits the device (needs reachable creds in env/.env)
bunx @modelcontextprotocol/inspector --cli bun run src/cli.ts serve \
  --method tools/call --tool-name list_interfaces --tool-arg type_filter=ether

bun run inspect:cli is a shortcut for the first one.

Multiple devicesCopy Anchor Link

When several devices are configured, every tool exposes a device argument. Target one from the CLI with --tool-arg device=<name>:

MIKROTIK_DEVICES='{"defaultDevice":"site-a","devices":{ … }}' \
bunx @modelcontextprotocol/inspector --cli bun run src/cli.ts serve \
  --method tools/call --tool-name get_system_identity --tool-arg device=site-b

In the UI the device field appears as a dropdown of your configured names.

Inspecting the HTTP transportCopy Anchor Link

Run the server over HTTP, then point the Inspector at it:

# Terminal 1 — serve over streamable-http
MIKROTIK_HOST=192.168.88.1 bun run src/cli.ts serve --transport streamable-http --mcp-port 8000

# Terminal 2 — connect the Inspector UI to it
bunx @modelcontextprotocol/inspector
# then in the UI choose Transport "Streamable HTTP" and URL http://127.0.0.1:8000/mcp
# (the mcp-inspector.config.json "mikrotik-http" entry is preconfigured for this)

Or open the UI straight at the right target: http://localhost:6274/?transport=streamable-http&serverUrl=http://127.0.0.1:8000/mcp.

TroubleshootingCopy Anchor Link