diff --git a/src/tools/background-task/constants.ts b/src/tools/background-task/constants.ts
index 9a2e1fc98..e7ff93b0e 100644
--- a/src/tools/background-task/constants.ts
+++ b/src/tools/background-task/constants.ts
@@ -2,6 +2,6 @@ export const BACKGROUND_TASK_DESCRIPTION = `Run agent task in background. Return
 
 Use \`background_output\` to get results. Prompts MUST be in English.`
 
-export const BACKGROUND_OUTPUT_DESCRIPTION = `Get output from background task. System notifies on completion, so block=true rarely needed.`
+export const BACKGROUND_OUTPUT_DESCRIPTION = `Get output from background task. Use full_session=true to fetch session messages with filters. System notifies on completion, so block=true rarely needed.`
 
 export const BACKGROUND_CANCEL_DESCRIPTION = `Cancel running background task(s). Use all=true to cancel ALL before final answer.`
diff --git a/src/tools/background-task/index.ts b/src/tools/background-task/index.ts
index 14cb4cea7..c769b07b8 100644
--- a/src/tools/background-task/index.ts
+++ b/src/tools/background-task/index.ts
@@ -5,3 +5,4 @@ export {
 
 export type * from "./types"
 export * from "./constants"
+export type { BackgroundOutputClient, BackgroundOutputManager, BackgroundCancelClient } from "./tools"
diff --git a/src/tools/index.ts b/src/tools/index.ts
index d749d427a..3eab094fc 100644
--- a/src/tools/index.ts
+++ b/src/tools/index.ts
@@ -35,6 +35,8 @@ export { createSkillMcpTool } from "./skill-mcp"
 import {
   createBackgroundOutput,
   createBackgroundCancel,
+  type BackgroundOutputManager,
+  type BackgroundCancelClient,
 } from "./background-task"
 
 import type { PluginInput, ToolDefinition } from "@opencode-ai/plugin"
@@ -47,9 +49,11 @@ export { createLookAt } from "./look-at"
 export { createDelegateTask } from "./delegate-task"
 
 export function createBackgroundTools(manager: BackgroundManager, client: OpencodeClient): Record<string, ToolDefinition> {
+  const outputManager: BackgroundOutputManager = manager
+  const cancelClient: BackgroundCancelClient = client
   return {
-    background_output: createBackgroundOutput(manager, client),
-    background_cancel: createBackgroundCancel(manager, client),
+    background_output: createBackgroundOutput(outputManager, client),
+    background_cancel: createBackgroundCancel(manager, cancelClient),
   }
 }