REPL Tools

Tools for interacting with a Kotlin REPL session.

kotlin_repl

Executes Kotlin code interactively within the project's full JVM classpath — use when you need to run code, not just read it.

Decision rule: - Need to understand an API's shape, signature, or behavior? → read its source with search_dependency_sources / read_dependency_sources. Instant, complete, no JVM needed. - Need to actually execute code — verify runtime behavior, experiment with your own logic, render UI? → use this tool.

After modifying project source code, stop then start to pick up classpath changes.

Commands

• start: Initialize a session. Requires projectPath and sourceSet.
• run: Execute a snippet. Session state (variables, imports) persists between calls.
• stop: Terminate the session and release JVM resources.

Input schema

{
  "properties": {
    "command": {
      "enum": [
        "start",
        "stop",
        "run"
      ],
      "type": "string"
    },
    "projectRoot": {
      "type": "string",
      "description": "Absolute path to Gradle project root (parent of gradlew and settings.gradle). Defaults to GRADLE_MCP_PROJECT_ROOT when omitted."
    },
    "projectPath": {
      "type": [
        "string",
        "null"
      ],
      "description": "Gradle project path (e.g., ':app'). Required for 'start'."
    },
    "sourceSet": {
      "type": [
        "string",
        "null"
      ],
      "description": "Source set (e.g., 'main', 'test'). Required for 'start'. Must be JVM-compatible."
    },
    "additionalDependencies": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "description": "Additional classpath dependencies (e.g., 'group:artifact:version')."
    },
    "env": {
      "type": "object",
      "additionalProperties": {
        "type": "string"
      },
      "description": "Environment variables for the REPL worker process."
    },
    "envSource": {
      "enum": [
        "NONE",
        "INHERIT",
        "SHELL"
      ],
      "description": "Where to get the base environment variables from. Defaults to INHERIT.",
      "type": "string"
    },
    "optIn": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "description": "List of annotations to opt-in to (e.g., 'kotlinx.coroutines.ExperimentalCoroutinesApi')."
    },
    "code": {
      "type": [
        "string",
        "null"
      ],
      "description": "Kotlin snippet to execute. Required for 'run'."
    }
  },
  "required": [
    "command"
  ],
  "type": "object"
}