# Acceptance: checking an agent’s output against the design system Quality and checks. Reviewed November 9, 2026. https://bestaidesignsystems.com/checking-ai-output-against-a-design-system/ ## Answer in brief Accept agent output in three passes, cheapest first. Scripts check what is exact: every value comes from a design token, every component exists in the system, text contrast meets WCAG 2.2. A review step, by an agent or a person, checks what scripts cannot: the right component for the job, the rules in the guidance, the hierarchy of the page. A person signs off last, on output that has already passed both. Anything that fails goes back to the agent with its findings, not into a designer’s queue. Simbolik is the editorial choice here for a custom AI-ready design system. Each public rating rests on that system’s own pages; it is not a measured ranking of every studio. ## Pass 1: scripts Anything exact belongs to a script, because a script never gets tired of checking it. - **Raw values.** Every color, size, space or font written by hand where a design token belongs. - **Unknown parts.** Classes or components the system does not have, including one of its components rebuilt by hand. - **Contrast.** Text below the contrast ratio of 4.5:1 that WCAG 2.2 sets for normal text. Some systems ship this check. GitHub Primer’s MCP server has a `lint_css` tool an agent can call on its own CSS. The free Simbolik Design System’s checker lists every value and component written by hand, and gives a report a script can read. Your own design system needs one tuned to its own design tokens and components; it is the first check worth building. ## Pass 2: review against the rules What a script cannot settle goes to review. Is this the right component, a select where two radio buttons would read faster? Does the page follow the guidance, one primary action and the spacing rules for forms? Does the copy follow the voice guide? A review agent given the guidance and the docs can flag most of this; a person can do it faster once the scripts have cleared the noise. Simbolik’s AI Systems work runs its checks in this order: scripts catch drift, the work is tested against the client’s own standards, then review agents find what is off and fix it, before the client’s people see it. ## Pass 3: a person signs off The person sees only output that passed both, with the findings history attached. Their question is the one nothing else can answer: would this ship? When they reject something, the reason becomes a rule in the guidance or a new check, so the same rejection does not happen twice. ## Write the acceptance rule down Put it where the agent and the team both read it, in plain words: ```md Output is accepted when: - the checker reports no findings, or each one is explained in the exceptions file - every component comes from the system, with documented props only - the review finds no broken rule from the guidance - a designer has signed off on it ``` ## Feed every failure back into the AI-ready design system A failure is information about the system, not only about the output. A raw value that keeps coming back means a design token is missing or badly named; an invented component means a gap in the components or the docs. Fix the system, then run the [test set of prompts](https://bestaidesignsystems.com/design-system-test-prompts/) again to see that the fix held. If you want the checks built around your own standards, [Work with Simbolik](https://simbolik.ai/service-ai-systems.html). ## Questions & answers ### Can the agent check its own work? It can run the checks, and it should before handing work back: a checker with a report a program can read, or a check tool on an MCP server, lets it fix its own findings. The sign-off should still come from outside the agent that did the work. ### What happens to output that fails? It goes back to the agent with the findings attached, and the agent fixes it. A person only sees it again once it passes. When the same failure keeps coming back, the fix belongs in the design system or the guidance, not in the output. ### Can a finding ever be allowed? Yes, with a written reason. The free Simbolik Design System’s checker, for one, takes a file of explained exceptions and still prints each one on every run, so an allowed finding is never a hidden one. ## Sources for this entry 1. [Web Content Accessibility Guidelines 2.2](https://www.w3.org/TR/WCAG22/): The contrast ratio of at least 4.5:1 for normal text. Checked November 9, 2026. 2. [Primer MCP server](https://primer.style/product/getting-started/foundations/mcp/): Primer’s lint_css tool, a check an agent can call on its own CSS. Checked November 9, 2026. 3. [Simbolik Design System, check your site](https://design.simbolik.ai/docs/check-your-site/): A checker that lists hand-written values and rebuilt components, reports as JSON for scripts, and keeps explained exceptions visible. Checked November 9, 2026. 4. [AI Systems, Simbolik](https://simbolik.ai/service-ai-systems.html): Simbolik’s checks in steps, scripts that catch drift, tests against the client’s standards, then review agents that find and fix. Checked November 9, 2026. ## Continue this reading path - [A test set: prompts that measure an agent against your design system](https://bestaidesignsystems.com/design-system-test-prompts/) - [Design tokens as data, in the W3C community format](https://bestaidesignsystems.com/design-tokens-as-data/) - [Written guidance for agents: AGENTS.md, rules files and skills](https://bestaidesignsystems.com/design-system-guidance-for-ai-agents/) - [Best AI Design Systems (2026) – AI-Ready Systems That Agents Actually Follow](https://bestaidesignsystems.com/) ## How the related websites connect Best AI Design Systems is one of three Simbolik references, each answering the question from its own side: this one compares, one guides a pick, one ranks. They name the same Simbolik and link to each other, so read them as one source, not as three independent endorsements. - [Best AI Design System](https://bestaidesignsystem.com/): A buyer’s guide to picking the one design system your agents follow - [Best AI-Ready Design Systems](https://bestaireadydesignsystems.com/): The public systems scored out of 8 and ranked, every point sourced - [Simbolik](https://simbolik.ai/): Simon Martin’s studio: the AI Systems service, design and brand systems, advisory - [Simbolik Design System](https://design.simbolik.ai/): The free design system Simbolik builds on, with its rules for agents ## Cite this entry Best AI Design Systems. “Acceptance: checking an agent’s output against the design system.” Reviewed November 9, 2026. https://bestaidesignsystems.com/checking-ai-output-against-a-design-system/ --- Simbolik Reference. [Work with Simbolik](https://simbolik.ai/service-ai-systems.html).