SEO agencies do four kinds of work: technical SEO (making sites crawlable, fast, and indexable), content SEO (researching, drafting, and optimising the pages that target search queries), authority building (earning links and citations), and reporting (translating organic search data into business decisions). Most agencies do one or two of these well and the others to varying degrees of competence.
I run organic search for HostList.io (28,000 programmatic-SEO pages) and across Seahawk Media client engagements. This is the operator view of what SEO agencies actually do day-to-day, what good work looks like, and how to tell whether the agency you have is delivering serious SEO or theatre.
Technical SEO
Technical SEO is the work that makes a site crawlable, indexable, and fast at search engines' satisfaction. Specific deliverables agencies in this space ship:
Site audits identifying crawl errors, broken redirects, missing schema, slow Core Web Vitals, mobile usability issues. Output: a prioritised remediation list with severity and traffic impact.
Indexability gates ensuring only content worth indexing reaches Google's index, while low-quality or duplicate pages get noindexed.
Schema markup implementation: Organization, BreadcrumbList, Article, BlogPosting, Product, FAQ, HowTo, LocalBusiness as appropriate per page type.
Hreflang setup for multi-language sites, including bidirectional reciprocity, x-default, and self-references.
Core Web Vitals optimisation: LCP, CLS, INP at 75th percentile field data.
Build-time SEO linting: a script in CI that fails the build on title-length, meta-length, hreflang, JSON-LD, or structured-data regressions.
Technical SEO is engineering-shaped work. Agencies without in-house engineering capacity white-label this to third parties, which adds coordination overhead and inconsistent quality.
Content SEO
Content SEO is the work that produces and optimises the pages that target search queries. Specific deliverables:
Keyword research: identifying the queries your business should target, by volume, intent, difficulty, and commercial value.
Content briefs: structured documents the writer (or AI tool plus human editor) uses to produce a page that ranks. Includes target query, intent, headings, citations to include, internal links to weave in.
Page production: drafting, editing, optimising for the target query and adjacent People Also Ask queries.
Internal linking: connecting new content into the site's existing topic clusters so authority flows correctly.
Refresh cycles: returning to existing content quarterly or annually to update facts, expand coverage, and re-rank pages that have drifted.
Content SEO is editorial-shaped work. The best content SEO agencies pair editorial talent with subject-matter expertise; the worst churn out generic LLM-generated content that triggers Helpful Content Update penalties.
Authority building
Authority building is the work that signals to search engines that your site is a credible source on its topics. The work splits into two halves:
Earned authority
Public relations, expert commentary, original research, partnerships with trusted publishers. The links and brand mentions that result are durable signals because they reflect genuine relationships.
Built authority
Outreach to publishers and bloggers requesting links to specific pages, guest posting, sponsored content with disclosure. Links from this work range from genuinely valuable to lightly transactional.
Avoid: paid links from PBNs, bulk guest-post networks, comment spam, or any "buy 10 high-authority links per month" service. These violate Google policy and the penalty is reliable.
Reporting and strategy
Reporting is where good agencies separate from theatrical ones. Specific deliverables you should expect from any serious SEO agency:
Monthly written report covering: traffic by source, conversion volume by source, ranking changes on priority queries, technical issues surfaced and fixed, content produced and published, links earned, AI Overview citation share, what failed and what worked.
Quarterly strategy reviews adjusting the work plan based on the data. Agencies that ship the same work plan for 12 months without adjusting based on results are running a packaged service.
Direct access to Search Console, GA4, and ranking tracker dashboards. Reporting via curated agency dashboards alone is a hiding-the-data signal.
What good SEO agencies do not do
Five things you should not see on the deliverable list of a serious SEO agency in 2026:
Buy links. The risk-to-reward is terrible and Google detection is reliable.
Mass-publish AI-generated content without human editing. Helpful Content Update penalty waiting to happen.
Promise specific rankings. Nobody can. Agencies that do are either lying or about to get clients penalised.
Charge significantly extra for SEO audits as a separate paid product. Audits are a foot-in-the-door, not a profit centre for serious agencies.
Report only on rankings without traffic and conversion data. Rankings are a leading indicator; outcomes are what matters.
How to evaluate an SEO agency on the first call
Five questions that separate serious agencies from theatre:
1. Walk me through a recent client engagement. What was the goal, what shipped, what failed, what would you do differently. Specific stories beat polished case studies.
2. Who specifically would work on my account, what is their seniority, what else are they handling. Vague answers about "the team" are a red flag.
3. What is your position on AI-generated content. The right answer is nuanced; categorical answers in either direction signal under-engagement with the topic.
4. Show me your reporting template. If they cannot share a sample, they do not have one.
5. What would make this engagement fail. Agencies that cannot articulate their own failure modes have not done the diligence required to run a serious engagement.
Bottom line
SEO agencies do technical SEO, content SEO, authority building, and reporting. The best agencies do at least three of the four well; the median does one well and the others to varying degrees. Match the agency to the work shape your business actually needs.
In 2026, the additional discriminator is AI surface coverage: Google AI Overviews, ChatGPT search, Perplexity, Bing Copilot. Agencies that ignore these surfaces are reporting on half the picture.
At Seahawk Media we run SEO across the full stack, technical, content, AI surface, and the discovery call is free.