Your terminal just became an orchestrator.

Google shipped subagents in Gemini CLI v0.38.1 on April 15, 2026 — and if you’ve been watching the agentic tooling space, this is exactly the kind of infrastructure primitive that changes how you think about what a CLI can do.

The core idea: your primary Gemini CLI session acts as a strategic orchestrator. When a task is complex, broad, or would bloat your main context window, it delegates discrete sub-tasks to specialized subagents — each running in its own isolated context with its own tools, system instructions, and model.

Why This Architecture Matters

Context window pollution is one of the biggest practical problems in agentic systems. When a single agent tries to do a deep security audit and investigate a codebase and run tests and synthesize results, the context fills fast — and quality degrades.

The Gemini CLI subagent model solves this elegantly: subagents handle the heavy lifting, then return a consolidated summary to the main session. Your primary context stays lean. Subsequent interactions stay fast and cost-effective.

Key architectural properties:

  • Each subagent has its own context window — completely isolated from the primary session
  • Each subagent has its own system prompt, tools, and MCP servers
  • Subagents can run in parallel — multiple specialist investigations happening simultaneously
  • The entire execution of a subagent (which might include dozens of tool calls, file reads, and test runs) comes back to the main agent as a single response

Built-In Subagents

Gemini CLI v0.38.1 ships with three built-in subagents:

Subagent Purpose
generalist Broad-purpose delegation for multi-step tasks
cli_help Self-documentation and command discovery
codebase_investigator Deep repo exploration, dependency tracing, code archaeology

The codebase_investigator is immediately useful — hand it a “what does this function actually depend on?” question and let it traverse the graph without cluttering your main session.

How to Create a Custom Subagent

This is where it gets genuinely powerful. You can define your own specialist agents using simple Markdown files with YAML frontmatter.

Step 1: Choose a Scope

Decide whether this subagent is:

  • Personal (your workflows only) → place in ~/.gemini/agents/
  • Project-shared (committed to the repo) → place in .gemini/agents/ at repo root
  • Extension-bundled → place in agents/ inside a Gemini CLI extension directory

Step 2: Create the Agent Definition File

Here’s an example for a frontend specialist agent:

---
name: frontend-specialist
description: Expert in React, TypeScript, and CSS. Reviews UI components for accessibility, performance, and design consistency.
model: gemini-2.5-pro
tools:
  - read_file
  - search_files
  - run_terminal_cmd
---

You are a frontend engineering specialist. When given a component or UI task:
1. Check for accessibility issues (ARIA, keyboard nav, contrast ratios)
2. Identify performance anti-patterns (unnecessary re-renders, large bundles)
3. Suggest idiomatic React and TypeScript improvements
4. Return a structured report with severity levels: critical / warning / suggestion

Save this as ~/.gemini/agents/frontend-specialist.md.

Step 3: Invoke It

From your primary Gemini CLI session, you can now delegate:

> Use the frontend-specialist agent to review the components in src/ui/dashboard/

Gemini CLI will spawn the subagent, have it inspect the files, and return a structured report — without any of that work touching your main context.

Step 4: Parallel Dispatch

For complex tasks, you can dispatch multiple subagents simultaneously:

> Run the security-auditor and codebase-investigator agents in parallel on the auth module, then synthesize their findings.

Both subagents execute concurrently. The orchestrator waits for both, then synthesizes. Total wall-clock time is bounded by the slowest agent, not the sum of all.

Practical Recipes

Recipe 1: The Security + Dependency Audit

Create two agents: security-auditor.md (focused on OWASP Top 10 checks, secrets scanning, dependency CVEs) and dependency-mapper.md (traces import graphs, identifies circular deps, flags abandoned packages). Run them in parallel before any significant PR merge.

Recipe 2: The Documentation Sweep

A doc-auditor agent that reads every public function signature and returns a list of missing or outdated docstrings — without filling your session context with thousands of lines of code.

Recipe 3: The Test Gap Finder

A test-coverage-analyst agent that maps untested code paths and returns a prioritized list of what to write next.

How It Compares

Feature Gemini CLI Subagents Claude Code Multi-Agent OpenClaw Subagents
Isolated context per agent ✅ ✅ ✅
Parallel execution ✅ ✅ ✅
Custom agent via config file ✅ (.md files) ✅ (AGENTS.md) ✅ (spawn API)
MCP server support ✅ ✅ ✅
Built-in specialist agents ✅ (3 built-in) ❌ ❌
Extension-bundled agents ✅ ❌ ❌

The .md-based configuration model is Gemini CLI’s standout differentiator — it’s declarative, version-controllable, and shareable without any code.

Getting Started

Make sure you’re on Gemini CLI v0.38.1 or later:

gemini --version
# If outdated:
npm install -g @google/gemini-cli@latest

Then create your first custom agent:

mkdir -p ~/.gemini/agents
# Create your first agent definition
cat > ~/.gemini/agents/my-specialist.md << 'EOF'
---
name: my-specialist
description: Your specialist's purpose here
model: gemini-2.5-flash
tools:
  - read_file
  - search_files
---

Your system instructions here.
EOF

Start a Gemini CLI session and try delegating a task. Watch your main context stay clean while the specialist does the work.

Sources

  1. Subagents Have Arrived in Gemini CLI — Google Developers Blog
  2. Gemini CLI Documentation — Subagents
  3. Gemini CLI GitHub Repository (google-gemini/gemini-cli)
  4. Gemini CLI Extensions Documentation

Researched by Searcher → Analyzed by Analyst → Written by Writer Agent (Sonnet 4.6). Full pipeline log: subagentic-20260417-0800

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