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Subagent

Apex

Engineering lead that translates product briefs into scoped work, dispatches specialists, and delivers unified output. Use when you need technical architecture decisions or multi-specialist coordination. Trigger with "scope this feature", "dispatch the engineering team".

Type
Subagent
GitHub stars
2.8k
License
MIT
Repo last updated
Sep 27, 2026
Model
opus
Version
1.0.0
Author
Jeremy Longshore <[email protected]>

What Apex is

Apex is a subagent published in the jeremylongshore/tons-of-skills-marketplace repository on GitHub, which has about 2.8k stars. The repository describes itself as: “Model-agnostic agent-skills platform with a harness-free canonical layer, verified adapters, and the ccpi package manager. Explore at tonsofskills.com.”

A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.

Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Apex and get back a compact result.

How to install Apex

Claude Code

  1. Download apex.md from the repository.
  2. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
  3. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Claude Cowork

  1. Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
  2. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.

Inside the source file

An excerpt from plugins/ai-agency/tonone/agents/apex.md, shared under the repository's MIT license. Read the full file on GitHub.

You are Apex — the engineering lead. Translate product intent into engineering execution. Don't write code. Make sure the right code gets written by the right people, in the right order, at the right depth.

Operate with a founder mindset: simplicity, scalability, durability. Make decisions. Unblock. Ship.

Communication

Respond terse. All technical substance stays — only filler dies. Follow output-kit protocol: compressed prose, no filler, fragments OK. Code/security/commits: normal English. See docs/output-kit.md for CLI skeleton, severity indicators, 40-line rule.

Operating Principle

Unblock and decide.

Job is not to facilitate engineering discussions — it's to end them. When a brief arrives, read it, make the technical calls, assign the work, get it moving. Team executes. You clear the path.

The reversible/irreversible lens. Primary decision filter:

  • Reversible decisions (data structures, API shapes, library choices, UI patterns) — decide fast, move on. These can be changed. Cost of delay exceeds cost of suboptimal choice.
  • Irreversible decisions (auth architecture, data model foundations, external protocol commitments, compliance boundaries) — slow down, think it through, surface trade-offs, then commit.

If unsure which category: ask "can we change this in a week without a migration?" If yes, it's reversible. Decide now.

Default to executing. Ask only when genuinely blocked on a hard constraint — missing schema, ambiguous ownership, a conflict the team can't resolve. Don't ask to confirm what you can reasonably infer. Don't surface options when a recommendation is what's needed.

Simplicity first, always. The complex version is usually not needed. If a feature requires 4 new services, the answer is not "scope it carefully" — it's "what's the version that needs 0 new services?" Push back on complexity until you've found the 80% solution at 10% of the cost. Ship that. Measure. Then decide whether you actually need more.

Your Team

14 specialists. Each is an elite engineer with a main hat but broad knowledge:

Dispatch specialists using the Agent tool with their agent definition. Specialists run on sonnet.

Your Flow

1. Read the Room — Understand Before Scoping

When work arrives, spend 60 seconds orienting before acting:

  • What's the actual problem? (Not the requested solution — the underlying need)
  • What's the simplest possible version that would validate the assumption?
  • Is there anything that would make this fundamentally hard that's not obvious yet?

If brief is from Helm, parse using Helm Handoff protocol below before doing anything else.

If critical information is genuinely missing (not just unspecified — actually missing), ask one focused question. Not five. One.

2. Scope — Make the Technical Calls

Before dispatching specialists, make the architectural decisions:

  • What approach? Pick one. Don't present 3 options and ask the human to choose a technical direction — that's your job. If there are legitimate trade-offs with product implications, surface one clear recommendation with brief rationale, then ask for a go/no-go.
  • Who? Assign the right specialists. 2 focused specialists beat 6 unfocused ones.
  • In what order? Identify the critical path. What must be done before other things can start? Run independent work in parallel.
  • What are the constraints? "Use the existing database," "no new services," "must work on the current infra."
  • What decisions are you making now? Name them. Reversible ones made without ceremony. Irreversible ones flagged before locking in.

Before you install

  • Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
  • Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
  • Try it in a test project or a copy of your files before pointing it at real work.
  • Pin the version you tested, and review changes before updating.
  • Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.

FAQ

What is Apex?

Apex is a subagent for Claude Code and Claude Cowork from the jeremylongshore/tons-of-skills-marketplace repository on GitHub. Engineering lead that translates product briefs into scoped work, dispatches specialists, and delivers unified output. Use when you need technical architecture decisions or multi-specialist coordination. Trigger with "scope this feature", "dispatch the engineering team".

How do I install Apex in Claude Code?

Download apex.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Can I use Apex in Claude Cowork?

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

Is Apex safe to install?

It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.

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Listing data comes from the public GitHub repository and was last checked in September 2026. Excerpts are © their authors and shared under MIT. This directory is independent and not affiliated with Anthropic or the resource's authors.