SubAgent invocation not working anymore on most recent nightly and Early access builds

Support Bug Reports
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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Bug Report: Task Tool Not Available for Subagent Invocation

Request ID

4e8121ff-582b-496b-9b28-10e6cbf62fbd

Date

2026-01-26

Summary

The Task tool for launching subagents is not available in the agent’s toolset, despite documentation indicating it should exist.

Environment

  • Cursor IDE:
    • Stable: Early Access Build 2.4.21 (issue present)
    • Nightly: Build 2.5 (issue present - Task tool VISIBLE but NOT AVAILABLE)
  • Model: Claude Opus 4.5
  • OS: Windows 11 (win32 10.0.26200 - Insider/Dev build)
  • Workspace: c:\Users\EddyE\Desktop\Web Projects\MCPage

Critical Finding on Nightly 2.5:

On the nightly build (2.5), the Task tool is visible in the toolset but not available for invocation. This suggests:

  • The tool exists and is being exposed
  • Something is blocking its actual use (permissions, feature flag, or bug)

Expected Behavior

According to Cursor documentation and user-created subagent files, the agent should have access to a Task tool that allows launching subagents with the following syntax:

<invoke name="Task">
  <parameter name="subagent_type">codebase-documenter</parameter>
  <parameter name="prompt">Document the module...</parameter>
</invoke>

Or functional equivalent:

Task(subagent_type="codebase-documenter", prompt="Document Vision Module")

Supporting Documentation Found:

  1. Cursor Official Docs (Subagents | Cursor Docs):

    • States “Agent automatically uses subagents when appropriate”
    • References built-in subagents: explore, bash, browser
    • Documents custom subagent creation in .cursor/agents/

  2. User’s AOT Command (~/.cursor/commands/aot.md):

    • References Task tool for subagent delegation
    • Shows batch invocation syntax for parallel subagent execution

  3. User’s Subagent Files (~/.cursor/agents/):

    • codebase-documenter.md - References Task() function
    • task-orchestrator.md - Designed to deploy task-executor agents
    • task-executor.md - Designed to be invoked by orchestrator
    • background-tasker.md - References Task tool for background execution

Actual Behavior

The agent’s available toolset does NOT include a Task tool.

Tools Actually Available:

  1. Shell
  2. Glob
  3. Grep
  4. LS
  5. Read
  6. Delete
  7. StrReplace
  8. Write
  9. EditNotebook
  10. TodoWrite
  11. ReadLints
  12. SemanticSearch
  13. WebSearch
  14. WebFetch
  15. AskQuestion
  16. CallMcpTool
  17. FetchMcpResource
  18. ListMcpResources
  19. SwitchMode

Task tool is MISSING.

Steps to Reproduce

  1. Open Cursor IDE with a workspace containing custom subagents in ~/.cursor/agents/
  2. Start a conversation with Claude Opus 4.5
  3. Ask the agent to launch a subagent (e.g., “use the codebase-documenter subagent”)
  4. Agent cannot find or invoke the Task tool
  5. Attempts to use CallMcpTool with “task” fail (not an MCP tool)

Attempted Workarounds:

Attempt Method Result

| 2 | TodoWrite with SUBAGENT prefix | Created todos, did not launch subagents |
| 3 | Grep for Task tool documentation | Found docs but tool unavailable |
| 4 | WebSearch for Cursor subagent API | Confirmed feature exists, still unavailable |
| 5 | Read AOT command showing Task syntax | Syntax confirmed, tool still missing |
| 6 | WebFetch official Cursor docs | Docs confirm feature, tool still missing |

Impact

  • Severity: Medium-High
  • User Impact: Cannot utilize parallel subagent execution for complex tasks
  • Workaround Available: Manual sequential execution (significantly slower)

Affected Workflows:

  • Parallel codebase documentation
  • Background task delegation
  • Task orchestration with multiple executors
  • AOT (Atom of Thoughts) subagent mode

Possible Causes

  1. Feature gating: Task tool may require specific Cursor plan (Max Mode?)
  2. Model restriction: May only be available to certain models
  3. Session type: May only work in specific agent modes
  4. Recent update regression: Update on 2026-01-26 may have affected tool availability
  5. Configuration required: May need explicit enablement in Cursor settings
  6. Tool exposure bug: On Nightly 2.5, tool is VISIBLE but NOT INVOCABLE - suggests a bug in tool registration or permissions

Version-Specific Behavior:

Version Task Tool Visible? Task Tool Usable?
Stable 2.4.21 No No
Nightly 2.5 Yes No

This pattern strongly suggests a bug in tool activation/permissions rather than intentional feature gating.

Additional Context

User’s Subagent Configuration:

~/.cursor/agents/
├── background-tasker.md      (is_background: true)
├── codebase-documenter.md    (PARALLEL execution capable)
├── frontend-design-advisor.md
├── task-checker.md
├── task-executor.md
├── task-orchestrator.md

Previous Session Reference:

User reports that “a previous Cursor session said that subagents are started via that internal task tool similar to todowrite” - indicating this functionality may have worked previously.

Requested Resolution

  1. Confirm whether Task tool should be available to Claude Opus 4.5
  2. If yes, investigate why it’s missing from the toolset
  3. Provide documentation on how to enable subagent invocation
  4. If feature-gated, document the requirements clearly

Attachments

  • Request ID: 4e8121ff-582b-496b-9b28-10e6cbf62fbd
  • Conversation includes 7 documented attempts to invoke subagents
  • Screenshots: N/A (text-based reproduction steps provided)

Steps to Reproduce

Ask to invoke subagents for Specific tasks

ask it to list internal tools it can call (on nightly it recognizes the Agents and the tool, how to invokeit but says its unavailable.
ON Early access it cant recognize the tool unless it reads the Sub agent descriptions)

Expected Behavior

Running multiple Subagents (and custom agents) within the same chat panel, was functional before

Operating System

Windows 10/11

Version Information

Early Access 2.4.21
Nightly 2.5 latest (though was persistent error for the last 2 days, while it worked flawlessly before)

Does this stop you from using Cursor

No - Cursor works, but with this issue

Sub-agent task broken in 2.4.22
My subagents can't be used in auto model
3

probably not but maybe!? is MAX MODE required for them to work now? cause before i didndt need to use max mode :slightly_smiling_face:

4

Hey, thanks for the report.

This is a known issue and other users have reported the same thing:

The team is aware and is looking into it. The issue is that even when subagent_delegation_context is injected into the prompt, the Task tool itself isn’t bound to the agent. There’s no timeline yet, but your report helps raise the priority.

About Max Mode, no, it’s not related. Subagents should work on the usage-based plan without Max Mode.

Can you share the Request ID with Privacy Mode turned off? That’ll help the team dig deeper:

  1. Cursor Settings (Ctrl+Shift+J / Cmd+Shift+J)
  2. Find “Privacy Mode” and turn it off temporarily
  3. Try to reproduce the issue in a new chat
  4. In the chat, click the three dots (top right) > Copy Request ID
  5. Send it here

After that, you can turn Privacy Mode back on right away.

1 Like
5

NOw working in

  • in regular version 2.4.21 it started working now (despite not before)
  • Nightly Version: 2.5.0-pre.31.patch.0 (system setup) works too
  • Early Access Version: 2.4.23 (system setup)

96bfde64-9413-4e5e-b2c7-a76f4d396c4c (not sure if this one will show up as it started in privacy mode and the last message was in share mode)
41a2948c-5aa6-4b7c-83b2-ef471c329d0f
7a8dc114-235b-454b-86c6-79d89e2807df

Sorry for the late reply and not sure if these requests are helpful now or not as it works now :slight_smile: