# Spawning subagents and passing context

*Claude Certified Architect - Foundations Study Guide · Agentic Architecture & Orchestration · Last updated October 22, 2026 · https://www.certifyforce.com/study-guide/claude-certified-architect-foundations/agentic-architecture-and-orchestration/spawning-subagents-and-passing-context*

What crosses the boundary when a coordinator spawns a subagent with the Task tool (now named Agent): only the delegation prompt, so findings, constraints and quality criteria must be written into it. Covers AgentDefinition fields, forks as the exception, structured hand-offs that keep source metadata, and parallel spawning in one response.

- Certification: Claude Certified Architect - Foundations
- Exam section: Agentic Architecture & Orchestration
- Study guide: https://www.certifyforce.com/study-guide/claude-certified-architect-foundations

**Official exam objective:**

> Configure subagent invocation, context passing, and spawning

## What the exam expects

- Explain the Task tool (now named Agent) as the spawn mechanism, and state both the exam guide's `allowedTools` claim and today's behaviour.
- Predict what a subagent can and cannot see, and put findings, constraints and rules where it will actually read them.
- Configure an `AgentDefinition` (description, prompt, tool restrictions, skills, model) and know which definition wins on a name clash.
- Pass context as structured records that keep content separate from metadata, and require structured final reports.
- Spawn independent subagents in parallel from one coordinator response, and write goal-and-criteria delegations instead of procedures.

Key terms: **Agent tool** (the tool a coordinator calls to spawn a subagent; formerly Task); **delegation prompt** (the Agent tool's prompt string, the only parent-to-subagent channel); **`AgentDefinition`** (programmatic subagent configuration); **fork** (a subagent that copies the conversation instead of starting fresh); **content/metadata separation** (findings kept apart from source URL, document and page).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Spawn tool name | Agent since v2.1.63; `Task(...)` still works as an alias | [Create custom subagents](https://code.claude.com/docs/en/sub-agents) |
| Parent-to-subagent channel | Only the Agent tool's prompt string | [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents) |
| Not inherited | Parent history, tool results, system prompt; skill content not listed in `skills` | [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents) |
| Subagent-to-parent channel | Final message only; intermediate tool calls stay inside | [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents) |
| Required `AgentDefinition` fields | `description` and `prompt` | [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents) |
| Name clash | Programmatic `agents` override filesystem agents | [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents) |
| Fork | Copies the conversation; start with `/subtask` or `subagent_type: "fork"` | [Create custom subagents](https://code.claude.com/docs/en/sub-agents), [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents) |
| `allowed_tools` | Auto-approves only; `Agent` does not ask before running | [Configure permissions](https://code.claude.com/docs/en/agent-sdk/permissions) |

## Check yourself

- Why must a coordinator restate a data-handling rule in the subagent's own prompt?
- When is a fork the right way to start a subagent?
- Which `AgentDefinition` fields are required?
- Why can't the coordinator read the URLs a subagent fetched unless the report lists them?
- How should a coordinator run four independent investigations fastest?

## Sources

- [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents)
- [Create custom subagents](https://code.claude.com/docs/en/sub-agents)
- [How we built our multi-agent research system](https://www.anthropic.com/research/multi-agent-research-system)
- [Parallel tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/parallel-tool-use)
- [Configure permissions](https://code.claude.com/docs/en/agent-sdk/permissions)
- [Work with sessions](https://code.claude.com/docs/en/agent-sdk/sessions)
- [Claude Certified Architect – Foundations Exam Guide v1.0](https://everpath-course-content.s3-accelerate.amazonaws.com/instructor%2F6nizmqk8tpzpfjvt6qmmav7rh%2Fpublic%2F1783542750%2FClaude+Certified+Architect+%E2%80%93+Foundations+Exam+Guide.pdf)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 13 linked practice questions, and unlimited timed mock exams are included with the Claude Certified Architect - Foundations pack (USD $19): https://www.certifyforce.com/practice-exams