Specified subagent model not used as expected with slash command in v3.13.25

Support Bug Reports
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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Cursor not respecting model defined in subagent file when slash command used.

I have an agent defined under

Steps to Reproduce

  1. Create agent file in project under .cursor/agents/my-test-agent.md with the following configuration:
---
name: my-test-agent
description: Example agent
model: 'claude-opus-5[effort=high]'
color: cyan
---
  1. Open Cursor UI in workspace, type slash command, then submit it.
/my-test-agent

Expected Behavior

Should use the Opus agent specified in my subagent file, but it used Auto instead (incorrectly)

Screenshots / Screen Recordings

CursorSubagentModelBug.png
CursorSubagentModelBug.png1074Ă—1060 104 KB

Operating System

Windows 10/11

Version Information

Cursor Version 3.13.25 (user setup)

For AI issues: which model did you use?

Auto, wanted to use Opus

Does this stop you from using Cursor

No - Cursor works, but with this issue

6

Hi @menotcomputer, thank you for the forum post!

You didn’t do anything wrong here, this is a bug on our side. Your file is valid YAML, where a quoted value and an unquoted one mean exactly the same thing, but the loader that reads agent files is treating the quote characters as part of the model name. That name matches nothing in our model catalog, and when a subagent’s model can’t be resolved, it currently falls back to the parent conversation’s model without telling you.

I tested both versions side by side: with the quotes the subagent ran on Auto, and with them removed, it ran on Opus 5 at high effort.

In the meantime, removing the quotes will unblock you:

---
name: my-test-agent
description: Example agent
model: claude-opus-5[effort=high]
color: cyan
---

This applies to any quoted value, so it’s worth leaving the quotes off even when you’re not using the bracket syntax.

One related thing that can look like part of the same problem but isn’t: running /my-test-agent from the composer doesn’t switch your main chat over to that agent’s model. The slash command hands the work to a subagent, and the model picker keeps showing your own selection (Auto Balance, in your screenshot) for the main conversation. The model to check is the one shown on the subagent’s task card.

I’ve reported this to the team so we can improve the handling of the subagents specified with quotes, but in the meantime hopefully the workaround of dropping the quotes works alright for you!

7

Thank you for the quick reply, Kevin!
I’ll unquote the frontmatter config for now as a workaround until there’s proper YAML support in place for Cursor agent and skill files.

Please let me know when this bug is fixed.

9

Any updates on valid YAML support in Cursor agent/skill files?

10

Hi @menotcomputer thanks for the post! I don’t have an update on this yet, but we are aware of the issue and the right eyes are on it. I’ll circle back here with any relevant updates!