Task tool not available to agent when subagent_delegation_context is injected (2.5.17, Windows)

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

When subagent delegation is enabled and subagent_delegation_context is injected (e.g. “delegate to ui-components”), the main agent does not have the Task tool in its toolset. Any attempt to delegate (e.g. “use the ui-components subagent” or “delegate to ui-components”) results in “Tool not found: Task”.

Expected: The agent should be able to call Task(subagent_type=“ui-components”, prompt=“…”) to delegate to custom subagents defined in ~/.cursor/agents/ (e.g. ui-components.md).

Actual: The Task tool is never available to the agent. The delegation context is injected (user has “delegate to ui-components” enabled), but the Task tool itself is not attached to the agent’s tools.

Environment:

  • Cursor 2.5.17 (user setup), Windows 10, Stable, Default track
  • Privacy Mode: disabled (tried with Share Data to rule out privacy-related issue)
  • Custom subagent: ~/.cursor/agents/ui-components.md with valid frontmatter (name, description)

Request ID: [הדבק כאן את ה-Request ID שתעתיק מהשיחה]

Steps to Reproduce

  1. Define a custom subagent in ~/.cursor/agents/ (e.g. ui-components.md) with valid YAML frontmatter (name, description).
  2. In Cursor Settings, enable delegation to that subagent (e.g. “delegate to ui-components”). Ensure Privacy Mode is off.
  3. Open a new Agent conversation in the project.
  4. Ask the agent to delegate to the subagent (e.g. “use the ui-components subagent for [task]” or “delegate to ui-components”).
  5. Observe: the agent responds with “Tool not found: Task” because the Task tool is not in its toolset, even though subagent_delegation_context was injected.

Expected Behavior

The main agent should have the Task tool available whenever subagent_delegation_context is injected. The agent should be able to call Task(subagent_type=“ui-components”, prompt=“…”) and the subagent should run in its own context. Custom subagents in ~/.cursor/agents/*.md should be discoverable and invokable by the main agent.

Operating System

Windows 10/11

Version Information

Cursor IDE 2.5.17 (user setup)
VSCode Version: 1.105.1
Commit: 7b98dcb824ea96c9c62362a5e80dbf0d1aae4770
Date: 2026-02-17T05:58:33.110Z
Build Type: Stable
Release Track: Default
OS: Windows_NT x64 10.0.26200

For AI issues: which model did you use?

COMPOSER & AUTO

For AI issues: add Request ID with privacy disabled

bbfabed6-438b-415b-b98a-c041f97d66c3

Additional Information

Custom subagent file: ~/.cursor/agents/ui-components.md (user-level). Subagent delegation is enabled in settings; subagent_delegation_context is injected into the prompt with “ui-components”. The agent receives the delegation instruction but the Task tool is never added to its available tools. Same behavior with Privacy Mode off. Related forum threads: Task Tool Missing for Custom Agents (149771), Sub-agent task broken in 2.4.22 (150210).

Does this stop you from using Cursor

No - Cursor works, but with this issue

3

Hey, thanks for the report. This is a known issue. Composer 1 doesn’t support the Task tool for subagents. When Auto is selected, requests often get routed through Composer 1, so subagents don’t work.

Workaround: pick a specific model from the dropdown instead of Auto or Composer, for example Sonnet 4.5, GPT-5.2, or Opus 4.5. The Task tool should show up.

Give that a try and let me know if it helps. If subagents still don’t work even on a specific model, please share the Request ID from this session, go to the three dots in the chat, then Copy Request ID, and we can take a closer look.

Related threads: