Show HN: Model Tools Protocol (MTP) – Forget MCP, bash is all you need

9 points

4 months ago

Recently I was trying to use an MCP server to pull data from a service, but hit a limitation: the MCP didn't expose the data I needed, even though the service's REST API supported it. So I wrote a quick CLI wrapper around the API. Worked great, except Claude Code had no structured way to know what my CLI does or how to call it. For `gh` or `curl` the model can learn from the extensive training data, but for a tool I just wrote, it was stabbing in the dark.

MCP solves this discovery problem, but it does it by rebuilding tool interaction from scratch: server processes, JSON-RPC transport, client-host handshakes. It got discovery right but threw out composability to get there. You can't pipe one MCP tool into another or run one in a cron job without a host process. Pulling a Confluence page, checking Jira for duplicates, and filing a ticket is three inference round-trips for work that should be a bash one-liner. I also seem to endlessly get asked to re-login to my MCPs, something `gh` CLI never asks me to do.

I think the industry took a wrong turn here. We didn't need a new execution model for tools, we needed to add one capability to the execution model we already had. That's what Model Tools Protocol (MTP) is: a spec for making any CLI self-describing so LLMs can discover and use it.

MTP does that with a single convention: your CLI responds to `--mtp-describe` with a JSON schema describing its commands, args, types, and examples. No server, no transport, no handshake. I wrote SDKs for Click (Python), Commander.js (TypeScript), Cobra (Go), and Clap (Rust) that introspect the types and help strings your framework already has, so adding `--mtp-describe` to an existing CLI is a single function call.

I don't think MCP should disappear, so there's a bidirectional bridge. `mtpcli serve` exposes any `--mtp-describe` CLI as an MCP server, and `mtpcli wrap` goes the other direction, turning MCP servers into pipeable CLIs. The ~2,500 MCP servers out there become composable CLI tools you can script and run in CI without an LLM in the loop.

The real payoff is composition: your custom CLI, a third-party MCP server, and jq in a single pipeline, no tokens burned. I'll post a concrete example in the comments.

Try it:

  npm i -g @modeltoolsprotocol/mtpcli && mtpcli --mtp-describe

I know it's unlikely this will take off as I can't compete with the great might of Anthropic, but I very much welcome collaborators on this. PRs are welcome on the spec, additional SDKs, or anything else. Happy building!

Spec and rationale: <https://github.com/modeltoolsprotocol/modeltoolsprotocol>

CLI tool: <https://github.com/modeltoolsprotocol/mtpcli>

SDKs: TypeScript (<https://github.com/modeltoolsprotocol/typescript-sdk>) | Python (<https://github.com/modeltoolsprotocol/python-sdk>) | Go (<https://github.com/modeltoolsprotocol/go-sdk>) | Rust (<https://github.com/modeltoolsprotocol/rust-sdk>)

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