Problems / Multi-agent and harness, hard

Fragile subagents

Eight subagents each call a tool that fails 1% of the time; any subagent failure fails the question.

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Your goals

Success ≥ 95% of tasks, p99 ≤ 90 s.

The traffic

8 requests a second for 45 seconds: 100% task (writes).

The system

What each component does in this design, and what calls it. The simulator mimics each one from these settings.

ComponentIts job hereSettings
Load balancerLoad balancerTraffic enters here.Calls Agent API.Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header.–
Agent APIApp serviceLoad balancer forwards to it.Calls Agent orchestrator.Little's law: throughput ≈ concurrency ÷ latency. 200 slots at 50 ms serve about 4,000 req/s.3 replicas × 500 slots · timeout 180 s
Agent orchestratorAgent orchestratorAgent API calls it.Calls Subagent pool.An agent loops: think, call a tool, read the result, repeat until done.400 slots · 1 steps
Subagent poolSubagent poolAgent orchestrator calls it.Calls MCP tool servers.Multi-agent research systems fan a task out to parallel subagents and use many times more tokens than a single agent.400 slots · 8 steps
MCP tool serversTool / MCP serverSubagent pool calls it.Tools give the model actions such as search or database queries; each call is another round trip.200 slots

Hints

Try it first. Open one hint at a time if you get stuck.

Hint 1

1 − 0.99⁸ ≈ 8%.

Hint 2

Fewer, better-scoped subagents.

One way to solve it

Reduce the fan-out.

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