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claude-code - 💡(How to fix) Fix Built-in /simplify skill fails: agent type 'code-simplifier' not found when code-simplifier plugin is installed [2 comments, 2 participants]

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anthropics/claude-code#51635•Fetched 2026-04-22 07:56:58
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The built-in /simplify skill fails with Agent type 'code-simplifier' not found when the code-simplifier plugin is installed from claude-plugins-official.

Error Message

code-simplifier(Code reuse review of process-admin-contact.php change)
  ⎿  Initializing…
  ⎿  Error: Agent type 'code-simplifier' not found. Available agents: general-purpose, statusline-setup, Explore, Plan,
     claude-code-guide, code-simplifier:code-simplifier, pr-review-toolkit:code-reviewer,
     pr-review-toolkit:silent-failure-hunter, pr-review-toolkit:code-simplifier, pr-review-toolkit:comment-analyzer,
     pr-review-toolkit:pr-test-analyzer, pr-review-toolkit:type-design-analyzer, feature-dev:code-reviewer,
     feature-dev:code-explorer, feature-dev:code-architect, technical-documentation-writer, senior-test-engineer,
     software-developer, senior-product-manager, senior-architect, security-reviewer

Root Cause

The built-in /simplify skill references the agent by its short name code-simplifier, but when installed via the plugin system, the agent is registered with a namespaced name: code-simplifier:code-simplifier (format: <plugin-name>:<agent-name>).

The built-in skill does not use the namespaced format, so the lookup fails even though the agent is present and enabled.

Fix Action

Workaround

Create a local .claude/commands/simplify.md that explicitly invokes code-simplifier:code-simplifier via the Agent tool with subagent_type: "code-simplifier:code-simplifier".

Code Example

code-simplifier(Code reuse review of process-admin-contact.php change)
  ⎿  Initializing…
  ⎿  Error: Agent type 'code-simplifier' not found. Available agents: general-purpose, statusline-setup, Explore, Plan,
     claude-code-guide, code-simplifier:code-simplifier, pr-review-toolkit:code-reviewer,
     pr-review-toolkit:silent-failure-hunter, pr-review-toolkit:code-simplifier, pr-review-toolkit:comment-analyzer,
     pr-review-toolkit:pr-test-analyzer, pr-review-toolkit:type-design-analyzer, feature-dev:code-reviewer,
     feature-dev:code-explorer, feature-dev:code-architect, technical-documentation-writer, senior-test-engineer,
     software-developer, senior-product-manager, senior-architect, security-reviewer
RAW_BUFFERClick to expand / collapse

Bug Report

Description

The built-in /simplify skill fails with Agent type 'code-simplifier' not found when the code-simplifier plugin is installed from claude-plugins-official.

Error Message

code-simplifier(Code reuse review of process-admin-contact.php change)
  ⎿  Initializing…
  ⎿  Error: Agent type 'code-simplifier' not found. Available agents: general-purpose, statusline-setup, Explore, Plan,
     claude-code-guide, code-simplifier:code-simplifier, pr-review-toolkit:code-reviewer,
     pr-review-toolkit:silent-failure-hunter, pr-review-toolkit:code-simplifier, pr-review-toolkit:comment-analyzer,
     pr-review-toolkit:pr-test-analyzer, pr-review-toolkit:type-design-analyzer, feature-dev:code-reviewer,
     feature-dev:code-explorer, feature-dev:code-architect, technical-documentation-writer, senior-test-engineer,
     software-developer, senior-product-manager, senior-architect, security-reviewer

Root Cause

The built-in /simplify skill references the agent by its short name code-simplifier, but when installed via the plugin system, the agent is registered with a namespaced name: code-simplifier:code-simplifier (format: <plugin-name>:<agent-name>).

The built-in skill does not use the namespaced format, so the lookup fails even though the agent is present and enabled.

Steps to Reproduce

  1. Install the code-simplifier plugin from claude-plugins-official
  2. Enable it in settings.json: "code-simplifier@claude-plugins-official": true
  3. Run /simplify in Claude Code

Expected Behavior

/simplify should successfully launch the code-simplifier agent using the correct namespaced type code-simplifier:code-simplifier.

Workaround

Create a local .claude/commands/simplify.md that explicitly invokes code-simplifier:code-simplifier via the Agent tool with subagent_type: "code-simplifier:code-simplifier".

Environment

  • Claude Code CLI (stable channel)
  • Plugin: code-simplifier@claude-plugins-official v1.0.0
  • OS: macOS Darwin 25.4.0

extent analysis

TL;DR

The most likely fix is to update the built-in /simplify skill to use the namespaced agent name code-simplifier:code-simplifier or apply the provided workaround.

Guidance

  • Verify that the code-simplifier plugin is correctly installed and enabled in settings.json.
  • Check the list of available agents in the error message to confirm that code-simplifier:code-simplifier is present.
  • Apply the provided workaround by creating a local .claude/commands/simplify.md file with the correct subagent_type to invoke the code-simplifier agent.
  • Consider reporting the issue to the plugin authors to update the built-in /simplify skill to use the namespaced agent name.

Example

// .claude/commands/simplify.md
{
  "type": "agent",
  "subagent_type": "code-simplifier:code-simplifier"
}

Notes

This workaround assumes that the code-simplifier plugin is correctly installed and enabled. If the issue persists, further investigation into the plugin or the Claude Code CLI may be necessary.

Recommendation

Apply the workaround by creating a local .claude/commands/simplify.md file, as this provides a temporary solution until the built-in /simplify skill is updated to use the correct namespaced agent name.

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claude-code - 💡(How to fix) Fix Built-in /simplify skill fails: agent type 'code-simplifier' not found when code-simplifier plugin is installed [2 comments, 2 participants]