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Plugin Transforms

Transforms let plugins change the definitions OpenCode uses for tools, agents, models, and other features. For example, a plugin can adjust a tool's description or choose a default agent.

This is useful when you're packaging a customized OpenCode experience for a team. The plugin can inspect existing definitions and apply changes in code.

Updating a Tool

Suppose you're working on a project that includes generated files. This plugin adds a reminder to the read tool's description:

import { Plugin } from "@opencode/plugin";

export default Plugin.define({
  id: "bootdev.generated-files",
  setup: async (ctx) => {
    await ctx.tool.transform((tools) => {
      tools.update("read", (tool) => {
        tool.description +=
          "\nFor generated files, find the source template before proposing edits.";
      });
    });
  },
});

ctx.tool.transform() lets the plugin inspect and modify OpenCode's tool definitions. tools.update("read", ...) then finds the read tool and makes the specified changes.

Assignment

Tell OpenCode to add a tool transform to .opencode/plugins/run-slop.ts, after the existing registration. Have it append this instruction to run_slop's description:

Use this tool to run individual .slop examples when checking language behavior. Use the test suite for regression testing.
/reload OpenCode and start a new session. Ask it to report run_slop's description and confirm the instruction appears. Review the diff: the tool's implementation should be unchanged.

Tell OpenCode to run and submit the CLI tests from the project root.