The documentation for the --cli mode is a bit lacking, but I got there in the end:

  npx @modelcontextprotocol/inspector --cli \
    https://agentic-mermaid.dev/mcp \
    --method tools/call \
    --tool-name render_svg \
    --tool-args-json '{"source":"graph TD; A-->B","options":{"padding":24}}'

Equivalent with my mcp-explorer tool:

  uvx mcp-explorer call \
    https://agentic-mermaid.dev/mcp render_svg \
    -a source 'graph TD; A-->B' \
    -a options '{"padding":24}'

So yeah, they're pretty similar.

Then for my list command:

  uvx mcp-explorer list https://agentic-mermaid.dev/mcp

With the inspector one you would do:

  npx @modelcontextprotocol/inspector --cli \
    https://agentic-mermaid.dev/mcp \
    --method tools/list

Mine returns a human-readable list (unless you add --json), the inspector one returns a big dump of raw JSON.

I would generally agree, but a word of caution for anyone trying it out from this thread: Try the latest pre 2.x version. The 2.0.0 that was released last week is highly broken even for some of the most common connection scenarios.

fast-agent is very good at this (disclosure: author)

you can specify --url, --npx and include --auth $TOKEN on the command line. you can also interactively connect with /connect, and pixel peep transport details https://fast-agent.ai/mcp/mcp-inspect-transport/