Content Freshness

Why freshness matters for AI agents

AI systems — both crawlers building training datasets and real-time agents answering queries — have a strong preference for recent, updated content. There are two reasons:

Accuracy: Outdated information leads to wrong answers. AI systems are aware of this and down-rank stale content for time-sensitive queries.
Training data cutoffs: LLMs are trained on data up to a cutoff date. Content published after that cutoff can be surfaced via RAG (Retrieval-Augmented Generation) pipelines that fetch live data — but only if the content is indexed and clearly dated.

The freshness signals stack

Signal	Where	Consumed by
`datePublished` in JSON-LD	`<script type="application/ld+json">`	Googlebot, AI crawlers, RAG systems
`dateModified` in JSON-LD	Same	Same
`<meta name="date">`	`<head>`	Some crawlers
`Last-Modified` HTTP header	Server response	HTTP caches, crawlers
URL date pattern	URL path	User signal only — avoid for SEO
`<lastmod>` in sitemap.xml	`/sitemap.xml`	All major crawlers
Visible date on page	Page content	User trust, E-E-A-T

JSON-LD date fields

The most reliable way to signal freshness:

{
  "@context": "https://schema.org",
  "@type": "Article",
  "headline": "Your Article Title",
  "datePublished": "2026-02-01T09:00:00+00:00",
  "dateModified": "2026-02-15T14:30:00+00:00",
  "author": {
    "@type": "Person",
    "name": "Author Name"
  }
}

Key rules:

Always use ISO 8601 format with timezone (T09:00:00+00:00)
dateModified should reflect meaningful content updates, not formatting fixes
Never backdate content — this signals to AI systems that you are manipulating freshness

sitemap.xml `<lastmod>`

The <lastmod> tag in your sitemap is a primary freshness signal for crawlers deciding which pages to re-index:

<url>
  <loc>https://example.com/docs/json-ld</loc>
  <lastmod>2026-02-15</lastmod>
  <changefreq>monthly</changefreq>
  <priority>0.8</priority>
</url>

In Next.js, generate the sitemap dynamically so lastmod reflects the actual updatedAt from your content frontmatter:

// app/sitemap.ts
export default async function sitemap(): Promise<MetadataRoute.Sitemap> {
  const docs = await getDocEntries("en");
  return docs.map((doc) => ({
    url: `${baseUrl}/docs/${doc.slug}`,
    lastModified: new Date(doc.updatedAt ?? doc.publishedAt),
    changeFrequency: "monthly",
    priority: 0.8,
  }));
}

Last-Modified HTTP header

For servers and CDNs, set the Last-Modified header to signal freshness at the HTTP level:

HTTP/1.1 200 OK
Last-Modified: Thu, 15 Feb 2026 14:30:00 GMT
Cache-Control: public, max-age=3600

In Next.js App Router:

export async function GET() {
  return new Response(content, {
    headers: {
      "Last-Modified": new Date(post.updatedAt).toUTCString(),
      "Cache-Control": "public, max-age=3600, stale-while-revalidate=86400",
    },
  });
}

Content refresh strategy

For documentation and blog posts, a structured refresh plan outperforms publishing new content haphazardly:

Evergreen content (docs, guides)

Review and update every 6–12 months
Add a visible "Last updated" notice at the top
Update dateModified in JSON-LD and <lastmod> in sitemap
Signal updates in-page: "Updated February 2026: section on X revised to reflect..."

News and time-sensitive content

Publish with a precise datePublished
Do not update after publication (to preserve date integrity)
If a correction is needed, add an explicit correction notice and update dateModified

Visible date signals on page

In addition to machine-readable signals, show the date visibly on the page:

<time datetime="2026-02-01T09:00:00+00:00">February 1, 2026</time>

The datetime attribute gives machines the precise value; the text inside gives humans a readable format. Both matter.

What to avoid

Hiding the publication date: decreases user trust and removes a key freshness signal
Inflating dateModified on trivial edits: gaming this signal undermines your credibility with AI systems
Stale content with no dateModified: AI systems assume the content is as old as datePublished
Date in URL as the sole freshness signal (e.g., /blog/2024/01/15/article): fragile and duplicates information better conveyed in JSON-LD

Impact on AI-generated answers

AI systems generating answers prefer the most recent, authoritative source. If your content is well-dated and regularly updated, you are more likely to be cited. The combination that works best:

ISO 8601 datePublished and dateModified in JSON-LD
<lastmod> in sitemap.xml kept current
Visible <time datetime="..."> on the page
Meaningful updates flagged in the content itself