support custom tools (#2668)

packages/plugin/src/example.ts

@@ -1,14 +1,20 @@
 import { Plugin } from "./index"
+import { tool } from "./tool"
 
-export const ExamplePlugin: Plugin = async ({
-  client: _client,
-  $: _shell,
-  project: _project,
-  directory: _directory,
-  worktree: _worktree,
-}) => {
+export const ExamplePlugin: Plugin = async (ctx) => {
   return {
     permission: {},
+    tool: {
+      mytool: tool((zod) => ({
+        description: "This is a custom tool tool",
+        args: {
+          foo: zod.string(),
+        },
+        async execute(args, ctx) {
+          return `Hello ${args.foo}!`
+        },
+      })),
+    },
     async "chat.params"(_input, output) {
       output.topP = 1
     },

packages/plugin/src/index.ts

@@ -10,7 +10,11 @@ import type {
   Auth,
   Config,
 } from "@opencode-ai/sdk"
+
 import type { BunShell } from "./shell"
+import { type ToolDefinition } from "./tool"
+
+export * from "./tool"
 
 export type PluginInput = {
   client: ReturnType<typeof createOpencodeClient>
@@ -18,34 +22,16 @@ export type PluginInput = {
   directory: string
   worktree: string
   $: BunShell
-  Tool: {
-    define(id: string, init: any | (() => Promise<any>)): any
-  }
-  z: any // Zod instance for creating schemas
 }
-export type Plugin = (input: PluginInput) => Promise<Hooks>
 
-// Lightweight schema spec for HTTP-registered tools
-export type HttpParamSpec = {
-  type: "string" | "number" | "boolean" | "array"
-  description?: string
-  optional?: boolean
-  items?: "string" | "number" | "boolean"
-}
-export type HttpToolRegistration = {
-  id: string
-  description: string
-  parameters: {
-    type: "object"
-    properties: Record<string, HttpParamSpec>
-  }
-  callbackUrl: string
-  headers?: Record<string, string>
-}
+export type Plugin = (input: PluginInput) => Promise<Hooks>
 
 export interface Hooks {
   event?: (input: { event: Event }) => Promise<void>
   config?: (input: Config) => Promise<void>
+  tool?: {
+    [key: string]: ToolDefinition
+  }
   auth?: {
     provider: string
     loader?: (auth: () => Promise<Auth>, provider: Provider) => Promise<Record<string, any>>
@@ -121,16 +107,4 @@ export interface Hooks {
       metadata: any
     },
   ) => Promise<void>
-  /**
-   * Allow plugins to register additional tools with the server.
-   * Use registerHTTP to add a tool that calls back to your plugin/service.
-   * Use register to add a native/local tool with direct function execution.
-   */
-  "tool.register"?: (
-    input: {},
-    output: {
-      registerHTTP: (tool: HttpToolRegistration) => void | Promise<void>
-      register: (tool: any) => void | Promise<void> // Tool.Info type from opencode
-    },
-  ) => Promise<void>
 }

packages/plugin/src/tool.ts

@@ -0,0 +1,20 @@
+import { z } from "zod/v4"
+
+export type ToolContext = {
+  sessionID: string
+  messageID: string
+  agent: string
+  abort: AbortSignal
+}
+
+export function tool<Args extends z.ZodRawShape>(
+  input: (zod: typeof z) => {
+    description: string
+    args: Args
+    execute: (args: z.infer<z.ZodObject<Args>>, ctx: ToolContext) => Promise<string>
+  },
+) {
+  return input(z)
+}
+
+export type ToolDefinition = ReturnType<typeof tool>