Sub-agent delegation allows a single coordinator agent to dynamically spawn specialized child agents and distribute tasks across them for parallel execution. The coordinator analyzes the main task, creates purpose-built sub-agents, assigns work, and aggregates results — all autonomously.
This capability is built on top of the autonomous agent mode (max_loops="auto") and uses two internal tools: create_sub_agent and assign_task.
How It Works
- Planning — The coordinator agent analyzes the task and determines what specialized sub-agents are needed
- Creation — The coordinator calls
create_sub_agent to spawn agents with specific names, descriptions, and system prompts
- Delegation — The coordinator calls
assign_task to distribute work to sub-agents, which execute concurrently
- Aggregation — Results from all sub-agents are collected and the coordinator synthesizes a final response
Enabling Sub-Agents
Sub-agent delegation requires two configuration settings on your agent:
| Parameter | Value | Purpose |
|---|
max_loops | "auto" | Enables the autonomous agent loop with tool access |
selected_tools | "all" or include "create_sub_agent" and "assign_task" | Grants the agent access to sub-agent tools |
When max_loops="auto" is set without specifying selected_tools, all safe default tools are enabled including sub-agent tools.
create_sub_agent
Creates and caches one or more specialized sub-agents on the coordinator.
| Parameter | Type | Required | Description |
|---|
agents | array | Yes | List of sub-agent specifications |
agents[].agent_name | string | Yes | Unique identifier for the sub-agent |
agents[].agent_description | string | Yes | Role and capabilities description |
agents[].system_prompt | string | No | Custom instructions for the sub-agent. Defaults to a description-based prompt |
sub-agent-{uuid} (e.g., sub-agent-a1b2c3d4) and is stored in the coordinator’s internal cache for reuse.
assign_task
Distributes tasks to previously created sub-agents for concurrent execution.
| Parameter | Type | Required | Description |
|---|
assignments | array | Yes | List of task assignments |
assignments[].agent_id | string | Yes | Target sub-agent ID from creation step |
assignments[].task | string | Yes | Task description to delegate |
assignments[].task_id | string | No | Assignment identifier. Defaults to task-{index} |
wait_for_completion | boolean | No | If true (default), waits for all results. If false, fire-and-forget dispatch |
API Usage
Sub-agents are used through the standard /v1/agent/completions endpoint. The coordinator agent autonomously invokes the sub-agent tools during its execution loop.
Basic Example
Python (requests)
Python (SDK)
TypeScript
Shell (curl)
import requests
import os
API_BASE_URL = "https://api.swarms.world"
API_KEY = os.environ.get("SWARMS_API_KEY", "your_api_key_here")
headers = {
"x-api-key": API_KEY,
"Content-Type": "application/json"
}
payload = {
"agent_config": {
"agent_name": "Research-Coordinator",
"description": "Coordinates parallel research across multiple domains",
"system_prompt": (
"You are a research coordinator. Break down complex research tasks "
"by creating specialized sub-agents for each domain, then delegate "
"research tasks to them and compile a comprehensive report from their findings."
),
"model_name": "gpt-4.1",
"max_loops": "auto",
"max_tokens": 8192,
"temperature": 0.3
},
"task": (
"Research the current state of quantum computing. Cover three areas in parallel: "
"1) Hardware advances (superconducting qubits, trapped ions, photonic systems), "
"2) Software and algorithms (error correction, quantum advantage demonstrations), "
"3) Commercial applications (finance, pharma, logistics). "
"Create a sub-agent for each area, assign research tasks, and compile a summary."
)
}
response = requests.post(
f"{API_BASE_URL}/v1/agent/completions",
headers=headers,
json=payload,
timeout=300
)
result = response.json()
print(result)
import os
from dotenv import load_dotenv
import json
from swarms_client import SwarmsClient
load_dotenv()
client = SwarmsClient(
api_key=os.getenv("SWARMS_API_KEY"),
base_url="https://api.swarms.world",
timeout=300,
)
result = client.agent.run(
agent_config={
"agent_name": "Research-Coordinator",
"description": "Coordinates parallel research across multiple domains",
"system_prompt": (
"You are a research coordinator. Break down complex research tasks "
"by creating specialized sub-agents for each domain, then delegate "
"research tasks to them and compile a comprehensive report from their findings."
),
"model_name": "gpt-4.1",
"max_loops": "auto",
"max_tokens": 8192,
"temperature": 0.3,
},
task=(
"Research the current state of quantum computing. Cover three areas in parallel: "
"1) Hardware advances (superconducting qubits, trapped ions, photonic systems), "
"2) Software and algorithms (error correction, quantum advantage demonstrations), "
"3) Commercial applications (finance, pharma, logistics). "
"Create a sub-agent for each area, assign research tasks, and compile a summary."
),
)
print(json.dumps(result, indent=4))
const API_KEY = process.env.SWARMS_API_KEY;
const BASE_URL = "https://api.swarms.world";
const payload = {
agent_config: {
agent_name: "Research-Coordinator",
description: "Coordinates parallel research across multiple domains",
system_prompt:
"You are a research coordinator. Break down complex research tasks " +
"by creating specialized sub-agents for each domain, then delegate " +
"research tasks to them and compile a comprehensive report from their findings.",
model_name: "gpt-4.1",
max_loops: "auto",
max_tokens: 8192,
temperature: 0.3,
},
task:
"Research the current state of quantum computing. Cover three areas in parallel: " +
"1) Hardware advances (superconducting qubits, trapped ions, photonic systems), " +
"2) Software and algorithms (error correction, quantum advantage demonstrations), " +
"3) Commercial applications (finance, pharma, logistics). " +
"Create a sub-agent for each area, assign research tasks, and compile a summary.",
};
const response = await fetch(`${BASE_URL}/v1/agent/completions`, {
method: "POST",
headers: {
"Content-Type": "application/json",
"x-api-key": API_KEY,
},
body: JSON.stringify(payload),
});
const result = await response.json();
console.log(JSON.stringify(result, null, 2));
curl -X POST "https://api.swarms.world/v1/agent/completions" \
-H "x-api-key: $SWARMS_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"agent_config": {
"agent_name": "Research-Coordinator",
"description": "Coordinates parallel research across multiple domains",
"system_prompt": "You are a research coordinator. Break down complex research tasks by creating specialized sub-agents for each domain, then delegate research tasks to them and compile a comprehensive report from their findings.",
"model_name": "gpt-4.1",
"max_loops": "auto",
"max_tokens": 8192,
"temperature": 0.3
},
"task": "Research the current state of quantum computing. Cover three areas in parallel: 1) Hardware advances, 2) Software and algorithms, 3) Commercial applications. Create a sub-agent for each area, assign research tasks, and compile a summary."
}'
selected_tools to control exactly which tools the coordinator can access:
payload = {
"agent_config": {
"agent_name": "Coordinator",
"model_name": "gpt-4.1",
"max_loops": "auto",
"selected_tools": [
"create_plan",
"think",
"create_sub_agent",
"assign_task",
"subtask_done",
"complete_task"
]
},
"task": "Your task here"
}
The full list of available tools for autonomous agents: create_plan, think, subtask_done, complete_task, respond_to_user, create_file, update_file, read_file, list_directory, delete_file, create_sub_agent, assign_task. The run_bash tool is not permitted.
Sub-Agents vs Other Multi-Agent Patterns
| Feature | Sub-Agent Delegation | Multi-Agent Swarms |
|---|
| Agent creation | Dynamic at runtime | Pre-defined in request |
| Endpoint | /v1/agent/completions | /v1/swarm/completions |
| Coordination | Single coordinator decides | Swarm architecture rules |
| When to use | Unknown number of agents needed, adaptive task decomposition | Known team structure, fixed workflows |
| Agent count | Determined by the coordinator at runtime | Specified upfront in the agents array |
Best Practices
- Clear coordinator prompts — Tell the coordinator explicitly that it should create sub-agents and delegate work. Include guidance on what types of specialists to create.
- 3-5 sub-agents for standard tasks, 5-10 for complex multi-domain projects. More than 10 increases coordination overhead.
- Specific sub-agent descriptions — The more specific the
agent_description, the better the sub-agent performs its specialized task.
- Use
wait_for_completion: true (default) when the coordinator needs to synthesize results. Use false only for fire-and-forget scenarios.
- Set appropriate timeouts — Sub-agent workflows take longer than single-agent calls since multiple agents run sequentially or in parallel. Use a timeout of 300+ seconds for complex tasks.
Cost Considerations
Sub-agent delegation uses more tokens than a single agent call because:
- The coordinator agent uses tokens for planning and synthesis
- Each sub-agent uses tokens for its specialized task
- Tool calls (create/assign) consume additional tokens
For cost-sensitive workloads, consider using a multi-agent swarm with pre-defined agents instead, which avoids the overhead of dynamic agent creation. 
