Custom model unavailable for explicit subagent selection

Support Bug Reports
,
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

A custom model works in the main Agent chat, but its model ID is missing from the available model list for explicit Task/subagent calls. The parent agent therefore refuses to select it explicitly.

Creating a custom subagent definition with the model ID pinned in its YAML frontmatter did not resolve the issue. I tested it both with and without force-default-model: true.

Using model: inherit successfully starts a general-purpose subagent when the parent chat uses the custom model. However, this ties model selection to the parent chat rather than allowing the custom model to be selected independently.

The model ID is represented below as my-custom-model for privacy.

Steps to Reproduce

  1. Configure a custom model and confirm it works in the main Agent chat.
  2. Ask the agent which models it can explicitly select when launching a Task subagent.
  3. Observe that the custom model ID is missing from the available list.
  4. Ask the agent to launch a subagent using that exact custom model ID. It refuses because the ID is not in its allowed model list.
  5. Create ~/.cursor/agents/custom-helper.md with YAML frontmatter containing name: custom-helper, description: General-purpose helper using a custom model, and model: my-custom-model. Replace the placeholder with the actual model ID.
  6. Attempt to invoke that custom subagent. The pinned definition does not resolve the issue.
  7. Repeat with force-default-model: true added to the frontmatter. This also does not resolve it.
  8. As a comparison, launch a general-purpose subagent with model: inherit from the custom-model parent chat. This starts successfully.

Expected Behavior

A custom model that supports subagent execution should be selectable explicitly through the Task tool or the model field in a custom subagent definition, rather than requiring the parent chat to use that model.

If explicit custom-model selection is unsupported, Cursor should document the limitation and show a clear diagnostic when a custom model is configured for a subagent.

Operating System

MacOS
Linux

Version Information

I am using macOS Cursor with an SSH connection into a Linux VM.

Version: 3.19.7 (Universal)
VS Code Extension API: 1.128.0
Commit: 90de2327392570a5f5f625c656c6749d228e6430
Date: 2026-09-02T23:03:07.739Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 42.10.0
Chromium: 148.0.7778.280
Node.js: 24.18.1
V8: 14.8.178.38-electron.0
xterm.js: 6.1.0-beta.291
OS: Darwin arm64 25.6.0

For AI issues: which model did you use?

A custom model, represented here as my-custom-model for privacy.

The explicit subagent model options reported in the session were inherit, claude-opus-5-thinking-high, and composer-2.5-fast. The custom model ID was absent.

Additional Information

The inherit workaround confirms successful subagent startup, but I have not independently verified the actual backend model or endpoint used. The subagent reported the expected model based on its context; that is not conclusive routing evidence.

Is filtering custom models out of explicit Task model selection intentional? Is there a supported way to make a custom model available for independent subagent selection?

Does this stop you from using Cursor

No - Cursor works, but with this issue

6

Hey @coreprocess, yes, this is intentional. Custom models you add yourself (or anything routed through your own API key) are deliberately left out of the explicit subagent model list, so a subagent can’t be pinned to one via the Task tool or a model: field. That’s why the frontmatter definition falls back to the parent’s model and force-default-model has no effect.

The supported way to run a subagent on a custom model is the one you found: select it in the parent chat and use model: inherit (or leave model unset). Subagents inherit the parent’s model, so they do genuinely run on your custom model there, not a different one.