diff --git a/packages/opencode/test/tool/tool-define.test.ts b/packages/opencode/test/tool/tool-define.test.ts
index a291b9f7f9..ca351cca48 100644
--- a/packages/opencode/test/tool/tool-define.test.ts
+++ b/packages/opencode/test/tool/tool-define.test.ts
@@ -1,11 +1,12 @@
-import { describe, test, expect } from "bun:test"
-import { Effect, Layer, ManagedRuntime, Schema } from "effect"
+import { describe, expect } from "bun:test"
+import { Effect, Layer, Schema } from "effect"
 import { Agent } from "../../src/agent/agent"
 import { MessageID, SessionID } from "../../src/session/schema"
 import { Tool } from "@/tool/tool"
 import { Truncate } from "@/tool/truncate"
+import { testEffect } from "../lib/effect"
 
-const runtime = ManagedRuntime.make(Layer.mergeAll(Truncate.defaultLayer, Agent.defaultLayer))
+const it = testEffect(Layer.mergeAll(Truncate.defaultLayer, Agent.defaultLayer))
 
 const params = Schema.Struct({ input: Schema.String })
 
@@ -21,49 +22,53 @@ function makeTool(id: string, executeFn?: () => void) {
 }
 
 describe("Tool.define", () => {
-  test("object-defined tool does not mutate the original init object", async () => {
-    const original = makeTool("test")
-    const originalExecute = original.execute
+  it.effect("object-defined tool does not mutate the original init object", () =>
+    Effect.gen(function* () {
+      const original = makeTool("test")
+      const originalExecute = original.execute
 
-    const info = await runtime.runPromise(Tool.define("test-tool", Effect.succeed(original)))
+      const info = yield* Tool.define("test-tool", Effect.succeed(original))
 
-    await Effect.runPromise(info.init())
-    await Effect.runPromise(info.init())
-    await Effect.runPromise(info.init())
+      yield* info.init()
+      yield* info.init()
+      yield* info.init()
 
-    expect(original.execute).toBe(originalExecute)
-  })
+      expect(original.execute).toBe(originalExecute)
+    }),
+  )
 
-  test("effect-defined tool returns fresh objects and is unaffected", async () => {
-    const info = await runtime.runPromise(
-      Tool.define(
+  it.effect("effect-defined tool returns fresh objects and is unaffected", () =>
+    Effect.gen(function* () {
+      const info = yield* Tool.define(
         "test-fn-tool",
         Effect.succeed(() => Effect.succeed(makeTool("test"))),
-      ),
-    )
+      )
 
-    const first = await Effect.runPromise(info.init())
-    const second = await Effect.runPromise(info.init())
+      const first = yield* info.init()
+      const second = yield* info.init()
 
-    expect(first).not.toBe(second)
-  })
+      expect(first).not.toBe(second)
+    }),
+  )
 
-  test("object-defined tool returns distinct objects per init() call", async () => {
-    const info = await runtime.runPromise(Tool.define("test-copy", Effect.succeed(makeTool("test"))))
+  it.effect("object-defined tool returns distinct objects per init() call", () =>
+    Effect.gen(function* () {
+      const info = yield* Tool.define("test-copy", Effect.succeed(makeTool("test")))
 
-    const first = await Effect.runPromise(info.init())
-    const second = await Effect.runPromise(info.init())
+      const first = yield* info.init()
+      const second = yield* info.init()
 
-    expect(first).not.toBe(second)
-  })
+      expect(first).not.toBe(second)
+    }),
+  )
 
-  test("execute receives decoded parameters", async () => {
-    const parameters = Schema.Struct({
-      count: Schema.NumberFromString.pipe(Schema.optional, Schema.withDecodingDefaultType(Effect.succeed(5))),
-    })
-    const calls: Array<Schema.Schema.Type<typeof parameters>> = []
-    const info = await runtime.runPromise(
-      Tool.define(
+  it.effect("execute receives decoded parameters", () =>
+    Effect.gen(function* () {
+      const parameters = Schema.Struct({
+        count: Schema.NumberFromString.pipe(Schema.optional, Schema.withDecodingDefaultType(Effect.succeed(5))),
+      })
+      const calls: Array<Schema.Schema.Type<typeof parameters>> = []
+      const info = yield* Tool.define(
         "test-decoded",
         Effect.succeed({
           description: "test tool",
@@ -73,27 +78,27 @@ describe("Tool.define", () => {
             return Effect.succeed({ title: "test", output: "ok", metadata: { truncated: false } })
           },
         }),
-      ),
-    )
-    const ctx: Tool.Context = {
-      sessionID: SessionID.descending(),
-      messageID: MessageID.ascending(),
-      agent: "build",
-      abort: new AbortController().signal,
-      messages: [],
-      metadata() {
-        return Effect.void
-      },
-      ask() {
-        return Effect.void
-      },
-    }
-    const tool = await Effect.runPromise(info.init())
-    const execute = tool.execute as unknown as (args: unknown, ctx: Tool.Context) => ReturnType<typeof tool.execute>
+      )
+      const ctx: Tool.Context = {
+        sessionID: SessionID.descending(),
+        messageID: MessageID.ascending(),
+        agent: "build",
+        abort: new AbortController().signal,
+        messages: [],
+        metadata() {
+          return Effect.void
+        },
+        ask() {
+          return Effect.void
+        },
+      }
+      const tool = yield* info.init()
+      const execute = tool.execute as unknown as (args: unknown, ctx: Tool.Context) => ReturnType<typeof tool.execute>
 
-    await Effect.runPromise(execute({}, ctx))
-    await Effect.runPromise(execute({ count: "7" }, ctx))
+      yield* execute({}, ctx)
+      yield* execute({ count: "7" }, ctx)
 
-    expect(calls).toEqual([{ count: 5 }, { count: 7 }])
-  })
+      expect(calls).toEqual([{ count: 5 }, { count: 7 }])
+    }),
+  )
 })