Architecture Review - Systematically Evaluating Workloads with AWS Well-Architected Tool
Explains architecture reviews of workloads using AWS Well-Architected Tool. Introduces evaluation based on the 6 pillars, building improvement plans, and using custom lenses.
The Well-Architected Framework and the Review Tool
The AWS Well-Architected Framework is a framework that organizes cloud architecture best practices into 6 pillars (operational excellence, security, reliability, performance efficiency, cost optimization, and sustainability). Well-Architected Tool is a managed tool that evaluates workloads based on this framework, identifying areas for architectural improvement through question-based reviews. Each pillar comes with multiple questions, and based on your answers, high-risk (HRI: High Risk Issue) and medium-risk (MRI: Medium Risk Issue) improvement items are identified automatically.
Evaluating Workloads and Improvement Plans
Using Well-Architected Tool starts with defining a workload. You specify the workload name, description, target AWS accounts, and Region, and select the lenses to apply (the AWS Well-Architected Framework Lens, the Serverless Lens, the SaaS Lens, and so on). When you answer the questions for each pillar, your compliance status with best practices is displayed on a dashboard. In the Improvement Plan, the list of HRIs and MRIs is displayed in order of priority, and specific improvement recommendations and links to reference documentation are provided for each item. With the milestone feature, you can save snapshots of evaluation results, then re-evaluate after implementing improvements and compare progress. The recommended operating pattern is to conduct reviews every quarter and track how improvements evolve with milestones.
Custom Lenses and Organizations Integration
Custom lenses are a feature for defining your organization's own best practices or industry-specific requirements as evaluation items. You define a lens in JSON format and can set up your own pillars, questions, best practices, and improvement plans. For example, you can create custom lenses that evaluate compliance with financial industry regulatory requirements, internal security policies, or specific architecture patterns. With Organizations integration, you can share custom lenses with all accounts in your organization and conduct reviews against unified evaluation criteria. There is no additional charge for using Well-Architected Tool itself, but being free is not the same as being unlimited. According to the official service quotas (as of August 2026), custom lenses are limited to 15 per account per Region, a single lens can be shared with up to 300 recipients, and up to 20 lenses can be associated with a single workload. All of these are fixed values that cannot be increased by request. In designs that distribute lenses across the organization, you narrow down their uses with these limits as a premise. Whereas Trusted Advisor performs automated resource-level checks (S3 public access settings, unused EC2, and so on), Well-Architected Tool performs interactive architecture-level reviews (Is the DR strategy appropriate? Is the monitoring setup sufficient?), so the two have a complementary relationship.
Well-Architected Tool Pricing
There is no additional charge for using Well-Architected Tool, and you are not billed for conducting reviews or saving milestones as such. You pay only for the AWS resources being evaluated. There is also no additional charge when you share custom lenses across your organization through the Organizations integration. However, being free is not the same as having no limit on how many you can create. According to the official service quotas (as of August 2026), the limits are 1,000 workloads per account per Region, 100 milestones per workload, and 500 review templates per account per Region, and none of them can be increased by request. In operations that consolidate hundreds of workloads in a single account, or that create a new workload for every review, it is safe to keep these limits in mind and decide naming conventions and account separation in advance. We recommend making regular quarterly reviews a habit and using them for continuous improvement of your architecture.
How to Think About the 6 Pillars
The Well-Architected Framework organizes the perspectives for evaluating good design into 6 pillars. Operational excellence asks whether you can continuously improve operations. Security asks whether data and systems are protected. Reliability asks whether you can recover from failures and meet demand. Performance efficiency asks whether you are using resources efficiently. Cost optimization asks whether you are avoiding unnecessary spending. Sustainability asks whether you are taking environmental impact into account. By examining workloads from multiple angles along these pillars, you can achieve a balanced design evaluation that is not biased toward any particular perspective.
Making Reviews a Habit
An architecture review is not something you do once and are done with. Because systems keep changing, it is important to review them regularly. Conducting reviews at milestones such as before major feature additions or configuration changes, or every quarter, lets you detect design drift and new risks early. Building reviews in as a checkpoint before production releases is also effective. By making reviews a habitual part of the development process, you can deal with problems before they accumulate and it becomes too late. Having a mechanism for continuous inspection is the key to keeping systems healthy over the long term.
Prioritizing Improvements
Even if a review finds many issues, addressing all of them at once is not realistic. You classify the detected items by risk level and address the serious ones first. Well-Architected Tool identifies high-risk items and helps you draw up an improvement plan. You set priorities along the lines of addressing serious risks related to security or reliability promptly and proceeding with lower-impact improvements in a planned way. You track the progress of your responses and confirm that risks are steadily decreasing. Concentrating limited resources on important improvements leads to effective architectural improvement.
Embedding a Culture of Design Improvement
The true value of Well-Architected lies not in using the tool itself but in rooting a culture of continuous design improvement in the organization. Having the common framework of the 6 pillars makes it easier for teams to discuss design with each other and aligns evaluation criteria. If you share what you have learned through reviews, the design capability of the whole organization is raised. If you evaluate across multiple workloads, common weaknesses and patterns of improvement become visible. Treating reviews not as a formality but as opportunities for learning and improvement fosters a strong design culture.
Summary - Guidelines for Using Well-Architected Tool
AWS Well-Architected Tool is a tool that systematically evaluates workload architecture against the 6 pillars. Its main strengths are question-based reviews, automatic identification of HRIs/MRIs, building improvement plans, and organization-specific evaluation through custom lenses. It is free to use, and we recommend conducting quarterly reviews of production workloads. It can also be used for pre-release reviews of new workloads.
References (Official AWS Resources)
The primary sources for this page are the official AWS website and documentation. Check the official pages below for the latest specifications and pricing.
- AWS Well-Architected Tool official page
- AWS Trusted Advisor official page
- AWS Config official page
- AWS Documentation (official)
If this page and the official documentation disagree, treat the official documentation as authoritative.