262.* with its bundled Kotlin plugin and Java 25 JBR.
1
Install the matched release
Run the installer from a terminal:In an interactive terminal, the installer offers to register Kast as a user-level MCP server with Codex. It installs the IDEA plugin and Kast service for the matched release line. On an upgrade, it removes prior versions that pass ownership checks. It asks before removing each older Kast entry it cannot fully verify; type
yes for that exact entry, or leave it in place. Noninteractive upgrades report and retain those entries.2
Restart IDEA and open your agent
Restart IntelliJ IDEA so it loads the plugin. Start the agent from the Kotlin repository or worktree you want Kast to inspect:Kast binds requests to that Gradle root, prepares the IDEA project, and waits for the required import and indexing state. No separate workspace-open or sync request is needed for an ordinary semantic query.
3
Ask a first question
Use Kast to query declarations in this workspace. Show one exact compiler-backed symbol with its kind, signature, source location, ref, and coverage. If no symbol is proven, explain the reason.
The query does not require a project-specific class name. Pass the returned ref unchanged to a later query or source read. See query examples for the direct tool input.Connect another client
Kast supports direct MCP and the included one-shot Tool RPC adapters from the same installation. The Codex App Server provides a hosted integration; its compatibility status is still preview. Each client should discover the installed catalog after installation or upgrade. The installer does not add a generalkast command to PATH. If another integration supplies the Codex MCP declaration, pass -- --skip-codex-mcp to the installer. For a second IDEA installation, pass -- --idea-home "/Applications/IntelliJ IDEA.app".
The MCP contract and Tool RPC contract show how other clients discover tools. If setup reports a blocker, use the troubleshooting guide.