Claude Code

Each Claude Code session is a single agent loop with its own context window, tools and permission mode. Parallelism is layered on top of that loop. Subagents run inside one session: Claude calls the Agent tool with a subagent type, the subagent works in a fresh context with its own tool allowlist and model, and only its summary returns. Subagents may nest up to three layers by default and can run in the foreground or background.

Beyond one session, agent view (claude agents, a research preview) dispatches and monitors background sessions, and cross-session messaging lets sessions pass findings. Agent teams, enabled with CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1, make the main session a fixed lead that spawns teammates as separate Claude Code instances; teammates message each other and share a task list, and cannot form nested teams. Dynamic workflows move the plan into a JavaScript script that fans out subagents and checks their results against each other.

Persistent knowledge lives in files: CLAUDE.md (or a repository's AGENTS.md) holds instructions, and auto memory stores notes Claude writes from your corrections. Worktrees give parallel sessions separate git checkouts; agent team members do not get worktrees automatically, so the docs advise partitioning files between them.

Permission modes decide what needs approval: default (Manual) prompts on first use of each tool, acceptEdits auto-accepts file edits, plan explores without editing, auto sends actions to a safety classifier, dontAsk denies anything that would prompt, and bypassPermissions skips prompts except for a documented set of protected actions. Allow and deny rules and managed policies refine this per tool, and hooks can run checks before or after tool calls. /tasks lists background work, including subagents, and lets you attach to or stop an item; claude agents shows which background sessions need input. In agent teams you can message any teammate directly and change an individual teammate's permission mode after it spawns.

curl -fsSL https://claude.ai/install.sh | bash

curl -fsSL https://claude.ai/install.sh | bash

# a project subagent with a narrow tool list and a cheaper model
mkdir -p .claude/agents
cat > .claude/agents/test-runner.md <<'EOF'
---
name: test-runner
description: Runs the test suite and reports failures. Use after code changes.
tools: Bash, Read, Grep
model: haiku
---
Run the tests and list each failing case with file and line.
EOF

claude mcp add --transport http notion https://mcp.notion.com/mcp
claude -p "Fix the date parser bug, then have the test-runner subagent verify" --allowedTools "Read,Edit,Bash"

# opt in to experimental agent teams, then start an interactive session
CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1 claude

• Requires a Pro, Max, Team, Enterprise or Console account (or a third-party provider such as Amazon Bedrock); the free claude.ai plan does not include Claude Code.
• The README marks npm installation as deprecated; if you still use npm install -g @anthropic-ai/claude-code, it needs Node.js 22+ (from v2.1.198), optional dependencies enabled, and never sudo.
• System requirements: macOS 13+, Windows 10 1809+, Ubuntu 20.04+, Debian 10+ or Alpine 3.19+, 4 GB RAM, internet access.
• In -p (print) mode the session starts in Manual permission mode, so pass --allowedTools or a permission mode for unattended edits.
• Enabling agent teams changes ordinary delegation: subagents that Claude names launch as teammates.
• Running several sessions, subagents or teammates multiplies token usage.

Yes. It connects to stdio and HTTP MCP servers added with claude mcp add, and claude mcp serve runs it as an MCP server for other clients. A2A and AG-UI support are not documented.

No. It requires a Pro, Max, Team, Enterprise or Console account, or a third-party provider such as Amazon Bedrock; plan prices are on claude.com/pricing. The repository's LICENSE.md reserves all rights under Anthropic's Commercial Terms.

Subagents run inside one session and report a summary back to the caller. Agent teams are separate Claude Code instances led by the main session that message each other and share a task list; they are experimental and must be enabled with CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1.

Yes: claude -p runs a task non-interactively, with --allowedTools or a permission mode deciding what may run without prompts; the Agent SDK does the same from Python or TypeScript.

Claude Code is proprietary and needs a paid Anthropic plan, Console billing or a supported cloud provider; OpenCode is MIT-licensed and works with many model providers. Both support subagents and MCP.