The SEO Agency Checklist: How to Evaluate Technical Audits, On-Page Optimization, and Site Performance

When you hire an SEO agency, you are not buying rankings. You are buying a systematic process for diagnosing technical barriers, aligning content with search intent, and improving the infrastructure that search engines use to evaluate your site. The difference between an effective engagement and a costly mistake often comes down to how well you understand the deliverables outlined in the proposal. This checklist breaks down the core services—technical SEO audits, on-page optimization, and performance tuning—into actionable evaluation criteria. Use it to brief your agency, review their work, and avoid the common pitfalls that derail campaigns.

1. Technical SEO Audit: Diagnosing Crawl, Index, and Site Health

A technical SEO audit is the foundation of any credible campaign. It examines how search engine bots discover, crawl, and index your pages. Without a clean technical baseline, even the best content and links will underperform. The agency should begin by analyzing your crawl budget—the number of URLs a search engine like Google will crawl on your site within a given timeframe. For large sites (10,000+ pages), inefficient crawl allocation can leave important pages unindexed for weeks. The audit must identify crawl waste, such as infinite parameter URLs, thin content pages, or broken internal links that consume budget without returning value.

The audit deliverables should include:

• Crawlability report: A list of pages blocked by `robots.txt` or returning 4xx/5xx status codes. Every blocked page that should be indexed is a missed opportunity.
• Index coverage analysis: Using Google Search Console data, the agency should show which pages are indexed, which are excluded, and why. Common reasons include “Crawled – currently not indexed” or “Discovered – currently not indexed.”
• XML sitemap validation: The sitemap must list only canonical, indexable pages. Including non-canonical URLs, redirect chains, or noindex pages pollutes the sitemap and confuses crawlers.
• Canonical tag audit: Every page with duplicate or near-duplicate content should have a self-referencing canonical tag. Misconfigured canonicals—pointing to the wrong URL or missing entirely—are a leading cause of index bloat.
• Duplicate content scan: Use a tool like Screaming Frog or Sitebulb to identify exact and near-duplicate pages. The agency should recommend consolidation (301 redirects or canonicalization) rather than relying on `noindex` tags alone.

Risk warning: An audit that only produces a list of errors without prioritizing them by business impact is not actionable. For example, a broken internal link on a top-traffic page is more urgent than a missing meta description on a low-traffic product page. The audit report must include a severity rating (Critical, High, Medium, Low) and a clear remediation path.

2. On-Page Optimization: Aligning Content with Search Intent

On-page optimization goes beyond keyword stuffing. Modern search engines evaluate whether a page satisfies the user’s intent—informational, navigational, commercial, or transactional. An agency’s on-page strategy should start with keyword research that groups terms by intent, not just volume. For instance, “best SEO tools” (commercial investigation) requires a different page structure and content depth than “how to do SEO” (informational).

The on-page deliverable should cover:

• Title tags and meta descriptions: Each page should have a unique, descriptive title tag that includes the primary keyword and matches the page content. Meta descriptions are not a ranking factor but influence click-through rate; they should be compelling and within 155–160 characters.
• Header structure (H1–H3): The H1 should match the page topic and include the primary keyword. Subsequent headers should create a logical content hierarchy. Avoid multiple H1s or skipping header levels (e.g., going from H1 to H3).
• Content optimization: The body copy should naturally incorporate related keywords (LSI or semantic terms) and answer common user questions. The agency should provide a content brief that includes target word count, recommended internal links, and a list of supporting topics.
• Internal linking: Every important page should receive internal links from relevant, high-authority pages on your site. The agency should map out a link graph that distributes link equity (PageRank) to deep pages.
• Image optimization: Images must have descriptive, keyword-rich alt text and be compressed for web delivery. Large, unoptimized images are a common cause of high Largest Contentful Paint (LCP) times.

Intent mapping is critical here. An agency that optimizes a transactional page (e.g., “buy SEO tools”) with informational content (e.g., “what is SEO”) will fail to convert. The on-page audit should include an intent assessment for each target keyword and a recommendation for page type (blog post, category page, product page, etc.).

3. Core Web Vitals and Site Performance: The Technical Performance Layer

Core Web Vitals—Largest Contentful Paint (LCP), First Input Delay (FID) / Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS)—are now part of Google’s ranking system. An agency that ignores performance is delivering an incomplete service. The performance audit should start with real-user monitoring data (Chrome User Experience Report, CrUX) rather than lab data alone, because synthetic tests can miss real-world variability.

The performance optimization checklist includes:

• LCP improvement: The largest content element (usually an image or text block) must load within 2.5 seconds. Solutions include server-side image compression, using next-gen formats (WebP, AVIF), implementing a CDN, and removing render-blocking resources. For image-heavy pages, lazy loading via `loading="lazy"` attributes is essential, but the LCP image should always load eagerly.
• CLS reduction: Cumulative Layout Shift measures visual stability. Common causes include images without explicit dimensions, dynamically injected content (ads, embeds), and web fonts that cause FOIT/FOUT. The agency should audit for missing `width` and `height` attributes and recommend `aspect-ratio` CSS for responsive images.
• FID/INP optimization: Input delay is tied to JavaScript execution. The agency should identify long tasks (scripts that block the main thread for more than 50ms) and recommend code splitting, deferring non-critical scripts, or moving to server-side rendering.
• Server response time: Time to First Byte (TTFB) should be under 200ms. If the server is slow, the agency should recommend a faster hosting provider, caching plugins, or a CDN.
• Lazy loading implementation: Use the `Intersection Observer API` for custom lazy loading or the native `loading="lazy"` attribute for images and iframes. Avoid lazy loading above-the-fold content, as this can hurt LCP.

Performance optimization is not a one-time fix. The agency should set up ongoing monitoring using tools like Lighthouse CI or WebPageTest, and provide a monthly performance report that tracks trends in LCP, CLS, and INP.

4. Link Building and Backlink Profile Management

Link building remains a high-risk, high-reward activity. A reputable agency will focus on earning links through content quality and outreach, not buying links or using private blog networks (PBNs). The backlink profile audit should include:

• Domain Authority (DA) and Trust Flow (TF) analysis: While these are third-party metrics (not Google’s), they help benchmark your profile against competitors. The agency should track the ratio of Trust Flow to Citation Flow—a large gap often indicates spammy links.
• Link quality assessment: Analyze referring domains for relevance, authority, and traffic. A link from a low-quality, unrelated site can do more harm than good.
• Disavow file management: If the agency finds toxic links (from link farms, hacked sites, or paid link networks), they should compile a disavow file and submit it to Google Search Console. But disavowing should be conservative—only links that are clearly manipulative or causing a manual action.
• Outreach strategy: The agency should provide a list of target domains, a sample pitch, and a timeline. Avoid agencies that promise a fixed number of links per month, as this often leads to low-quality placements.

Black-hat link building—using automated tools, buying links, or participating in link exchanges—can trigger a manual penalty. The agency must be transparent about their methods and provide a log of every link acquired. If they refuse to share the outreach process or the list of linked domains, that is a red flag.

5. Content Strategy and Keyword Research Integration

Content strategy is the bridge between technical SEO and on-page optimization. The agency should map your existing content to the buyer’s journey and identify gaps where new pages are needed. The keyword research phase must go beyond head terms and include long-tail queries that capture users with high purchase intent.

The content strategy deliverable should include:

• Keyword clusters: Group keywords by topic and intent. For example, “SEO audit tools” (commercial) and “how to run an SEO audit” (informational) belong in the same cluster but require different page types.
• Content gap analysis: Compare your site’s coverage against top-ranking competitors for your target keywords. Identify topics where you have no content or thin content.
• Editorial calendar: A monthly plan that includes target keywords, recommended word counts, internal linking opportunities, and promotion channels (social, email, outreach).
• Content refresh schedule: Old content that ranks on page 2–3 can often be updated to improve performance. The agency should flag pages with declining traffic and recommend updates.

A content strategy without a measurement framework is incomplete. The agency should define KPIs for each piece of content: organic traffic, keyword rankings, time on page, and conversion rate (if applicable).

6. Analytics, Reporting, and Ongoing Optimization

The final layer of an agency engagement is reporting. A good report is not a vanity dashboard of “impressions up 20%.” It should connect SEO activities to business outcomes: leads, sales, or revenue. The reporting framework should include:

The agency should also provide a monthly action plan based on the data. For example, if a high-traffic page has a high bounce rate, the on-page content may need revision. If a new page is not being indexed, the agency should review the internal linking and sitemap.

7. Red Flags and Risk Mitigation

Not all agencies operate with the same level of care. Watch for these warning signs:

• Guarantees of “first page rankings”: No ethical agency can guarantee rankings. Google’s algorithm is proprietary and changes frequently.
• Black-hat tactics: If the agency mentions “automated link building,” “link pyramids,” or “private blog networks,” walk away. These methods can lead to a manual penalty that takes months to recover from.
• No technical audit upfront: An agency that skips the technical audit and jumps straight to content or links is ignoring the foundation. Technical issues can undermine all other efforts.
• Vague reporting: If the report only shows “traffic up” without explaining why, the agency is not providing value. You need to see the correlation between actions and results.
• No mention of Core Web Vitals: Given that these are ranking signals, any agency that does not address site performance is behind the industry standard.

Summary Checklist for Briefing an SEO Agency

Before signing a contract, ask the agency to confirm the following in writing:

1. Technical audit scope: Will they crawl the entire site, or just a sample? Will they provide a prioritized fix list?
2. On-page optimization process: How do they determine intent? Do they provide content briefs or write the content themselves?
3. Performance optimization: Do they track Core Web Vitals using CrUX data? What is their approach to lazy loading and image optimization?
4. Link building methods: Can they share examples of past outreach? Do they have a process for disavowing toxic links?
5. Reporting frequency and depth: What metrics are included? How do they tie SEO activities to business outcomes?
6. Risk management: What is their policy on algorithm updates? How do they handle manual penalties?

A thorough agency will welcome these questions. One that avoids them is likely cutting corners. Use this checklist to evaluate proposals, review deliverables, and hold your agency accountable for measurable, sustainable results.

For further reading on specific performance techniques, see our guides on lazy loading best practices, image optimization for SEO, and fixing Cumulative Layout Shift.