Tiny update: The EMCP server now supports Prompts, Resources, and ResourceTemplates . You probably won’t use them because e.g. Claude Code doesn’t expose these functions to you, only Tools. Still, with these new features in place, the MCP server is now feature-complete

Release v0.3.1 and v0.3.2

I added three new configuration options to the StreamableHTTP plug:

1. allowed_origins + validate_origin
   • This allows you to restrict MCP calls to certain domains. CLI clients don’t send the Origin header though, so shouldn’t be affected.
2. recreate_missing_session
   • EMCP recreates expired or unknown sessions by default. This is a trade-off to UX which I’ve motivated further in the Readme. It is not spec-compliant though, so if you want to run in “strict” mode and reject unknown sessions or force clients to re-initialize a session if it expires, you can now do so by adding recreate_missing_session: false to your plug.

See the Changelog here
https://github.com/PJUllrich/emcp/blob/main/CHANGELOG.md

And documentation of these configurations here
https://github.com/PJUllrich/emcp?tab=readme-ov-file#origin-validation

This is great! Thanks for building it. It’s a much nicer, simpler implementation than other libraries I’ve seen and looks like it will be easy to extend and maintain. A couple of thoughts for feedback:

1. A pluggable session store would be great - many Elixir deployments can’t use clustering, so can’t rely on ETS.
2. It would be nice to have all the config for the server in its own module, rather than global config. This would allow multiple MCP servers to coexist, for example. Perhaps it could use the Ecto Repo pattern of use EMCP.Server, tools: [...] ?

(I might even get a chance to submit a PR for these…)