System design

Designing an Effective Agentic AI System

What is the simplest architecture that meets this workflow’s quality, control and operating requirements?

Reference notes by Min · Reviewed October 15, 2026

Working governance definitionAlso: best agent architecture · agent system design · workflow versus agent · agent reference architecture2 primary references

Definition

Agent architecture selection chooses how models, deterministic software, tools, state and human decisions work together to achieve a specified outcome within operational constraints.

Begin with the service contract: who needs what outcome, which errors matter, what data is available and which actions may change the world. A system that only summarizes documents has different requirements from one that modifies customer accounts. Similar chat interfaces can conceal very different engineering needs.

What it covers

Task
Define accepted outcomes, uncertainty and consequential actions.
Baseline
Compare ordinary software, retrieval, fixed workflows and adaptive agents.
Boundaries
Place authorization, validation and resource limits at execution boundaries.
Evidence
Evaluate usefulness, failures, cost, latency and recovery before expansion.

A practical reference design has request intake, task state, a planner or fixed workflow, a policy-enforced tool boundary, outcome verification and an operational record. Human approval enters where the consequences require it. These are responsibilities, not necessarily separate services or a mandatory technology stack.

In practice

Practical design patterns by Min.

  • Start with a task specification and representative evaluation cases.
  • Choose a fixed workflow when the required steps are known; add adaptive planning where evidence supports it.
  • Document trade-offs and release a bounded version with an accountable owner.

Select components by measured contribution. An extra planning loop, retrieval stage or specialist agent should resolve an observed problem that a simpler design cannot handle adequately. Record its effect on completion quality, prohibited actions, latency, cost and operational complexity.

Research notes

Source-grounded details and editorial applications. Follow each link for the original document.

Choose complexity deliberately

Anthropic distinguishes predetermined workflows from agents that dynamically direct their work and recommends starting simply. This article’s reference responsibilities are an editorial synthesis, not a mandated vendor architecture.

Source: Anthropic: Building effective agents ↗

Design depends on deployment context

The NIST AI RMF connects risk management with context, measurement and ongoing management. It does not rank agent frameworks or identify one universally best design.

Source: NIST AI RMF: Core functions and subcategories ↗

Working example

A procurement assistant

The system must find options, compare terms and prepare a purchase without exceeding delegated authority.

  1. Use deterministic calculations for totals and policy checks; use models for interpreting unstructured descriptions.
  2. Require a reviewable proposal and explicit approval before a consequential purchase.
  3. Record the transaction result, reconcile uncertain outcomes and compare quality and cost with the existing process.
Illustrative scenario, not a reported deployment.

Why the controls matter

The procurement example separates judgment from execution. A model can help interpret a supplier description, while ordinary software checks arithmetic and current limits. A verified purchase receipt establishes the external outcome; the model’s narrative alone does not. Recovery must handle a timeout after submission.

Common pitfalls

  • Equating more agents with a better architecture.
  • Using model instructions as the only authorization control.
  • Optimizing a demo without measuring maintenance, failure recovery or user outcomes.

Treat the design as a versioned hypothesis. Pilot with limited data and authority, inspect failures, and revise the relevant component. Expand only when the evidence supports the broader use. Keep rollback, ownership and ongoing evaluation in the design from the beginning.

Questions for operational review

Use these questions to decide what evidence your team needs. They are editorial prompts, not a compliance checklist.

  • Could a simpler workflow meet the same requirements?
  • Where are permissions and budgets actually enforced?
  • What evidence justifies each added component?

References

Primary documents reviewed for this entry. Examples and implementation patterns are editorial synthesis.

  1. Anthropic: Building effective agents ↗Accessed October 15, 2026
  2. NIST AI RMF: Core functions and subcategories ↗Accessed October 15, 2026