When are custom thresholds worth it for Body text large enough to read?
When are custom thresholds warranted?
Override when you have an accessibility commitment stricter than "not unreadable" and want the check to enforce it. Raising `minPx` to 14 or 16 turns a defect detector into a design-system gate, which is the right move when your team has published a minimum reading size and wants every page held to it automatically. Lowering `maxPx` is worth it on templates where you know the largest legitimate body element and want tighter detection of cascade leaks.
When should you stay on Standard?
Stay on the defaults if you have not actually agreed a minimum reading size internally, because the check will start failing pages over a number nobody signed off on and the findings will be argued with instead of fixed. Keep the Standard range on third-party or marketing pages you do not control the CSS for — you cannot change CSS you do not own, and a permanently failing check trains people to ignore it. If your goal is simply "tell me when a page breaks", the defaults already do that.
What do you trade away?
A raised `minPx` produces more findings, and the findings become opinions rather than defects — you have to be willing to treat them as work. Because a tighter floor fires on pages that are perfectly usable, the cost is credibility: a check that fails on something the team will not fix is worse than no check. Tightening `maxPx` has the opposite risk, quietly passing a genuine cascade leak that happens to land inside your narrowed window.
Community Standard vs org Custom
The Standard range is a shared floor: it is written to be defensible on any page, from any organisation, without configuration. Your Custom range is a statement about *your* type system and belongs to you — it should come from a published design token or accessibility policy you can point at, not from a number chosen during one audit. Record where the value came from, because a threshold nobody can source is the first thing relaxed the next time it fails.
Worked override examples
A documentation site with a published 16px minimum sets `minPx` to `16px` and leaves `maxPx` alone, turning the check into an enforcement of its own standard. A marketing team whose templates cap body copy at 20px sets `maxPx` to `24px` to catch heading rules leaking into paragraphs early, accepting that legitimate display type must then be excluded from the audited pages. A team auditing a partner-hosted page they cannot edit keeps both defaults, because the only actionable finding there is text that has genuinely broken.
How does an agent call it with parameters?
{
"type": "url",
"url": "https://example.com",
"validations": [
{
"id": "font-size-body-min-max",
"parameters": {
"minPx": "6px",
"maxPx": "48px"
}
}
]
}