Publishing Agent Extensions

Publishing to crates.io

The simplest way to distribute an agent extension is to publish it to crates.io. Symposium can install extensions directly from crates.io using cargo binstall (for pre-built binaries) or cargo install (building from source).

To make your agent extension installable:

1. Publish your crate to crates.io as usual
2. Include a binary target that speaks MCP over stdio
3. Optionally add [package.metadata.symposium] for configuration (see Creating Extensions)

That’s it. Users can reference your extension by crate name, and crate authors can recommend it in their Cargo.toml (see Recommending Extensions).

Publishing to the ACP Registry (optional)

The ACP Registry is a curated catalog of extensions with broad applicability. Publishing here is appropriate for:

• General-purpose extensions like Sparkle (AI collaboration identity) that help across all projects
• Language/framework extensions that benefit many projects
• Tool integrations that aren’t tied to a specific library

For crate-specific extensions (e.g., an extension that helps with a particular library), crates.io distribution with Cargo.toml recommendations is more appropriate. Users of that library will discover the extension through the recommendation system.

Submitting to the Registry

1. Fork the registry repository
2. Create a directory for your extension: my-extension/
3. Add extension.json:

{
  "id": "my-extension",
  "name": "My Extension",
  "version": "0.1.0",
  "description": "General-purpose extension for X",
  "repository": "https://github.com/you/my-extension",
  "license": "MIT",
  "distribution": {
    "cargo": {
      "crate": "my-extension"
    }
  }
}

4. Submit a pull request

Distribution Types

Extensions in the registry can specify different distribution methods:

For Rust crates, cargo distribution is recommended - it leverages the existing crates.io infrastructure.