Both Semrush and Ahrefs now let Claude, ChatGPT and other AI assistants query their data directly through MCP. Instead of opening a report, you ask "what does this competitor rank for that I don't?" and the assistant pulls the numbers itself.
On paper the two look almost the same: official remote servers, a sign-in instead of a config file, and access included in paid plans. In practice they differ in how much a question costs, how many rows you can pull, and how the assistant talks to them.
For this comparison I used the Semrush MCP for real while researching this article, and I logged how many API units each request used. I do not have an Ahrefs subscription, so the Ahrefs side is based on its official documentation, pricing page and unit formula, not on my own test. I also build RankBuddy, which has its own SEO MCP server, so I mention it once near the end and keep it out of the head-to-head.
Quick answer: connect the MCP of the tool you already pay for. The cheapest way into Ahrefs MCP is Lite at $129 a month with 200,000 API units. Semrush lists MCP access on its Starter plan at $199 a month, with 50,000 units. In my test a typical three-report question on Semrush used about 190 units, which is roughly 260 such questions a month. Ahrefs gives you four times as many units, but it caps Lite at 100 rows per request and charges a minimum of 50 units per call. Neither is worth buying just for the MCP.
Semrush MCP vs Ahrefs MCP at a glance
Prices and limits as listed on each vendor's site in October 2026.
| Semrush MCP | Ahrefs MCP | |
|---|---|---|
| Cheapest plan with MCP | Starter, $199 a month ($165.17 billed annually); Semrush's docs also list the legacy SEO Classic Pro and Guru plans | Lite, $129 a month |
| API units included | 50,000 per billing period | 200,000 a month on Lite, 800,000 on Standard, 2 million on Advanced |
| How a request is charged | Per row returned, by report type (10 units per row in my test for keywords) | 50 units minimum, otherwise rows × the cost of the fields you request |
| Rows per request | Set by your query; no plan cap documented | 100 on Lite, 250 on Standard, 500 on Advanced |
| More units | Unit packages from 2 million, only with Semrush One Advanced or SEO Classic Business | Higher plan, or extra units on Enterprise |
| Server URL | https://mcp.semrush.com/v2/mcp |
https://api.ahrefs.com/mcp/mcp |
| Sign-in | OAuth with your Semrush account, or an API key header | Consent screen that creates an MCP API key |
| Official apps | Claude, ChatGPT, Perplexity; config for Cursor, VS Code, Gemini CLI | Claude, ChatGPT, Copilot Studio, Le Chat, n8n and others |
| Access | Read-only | Almost entirely read operations |
| Data you get | Keywords, domains, organic and paid rankings, backlinks, competitors; Position Tracking and Site Audit projects (read-only) | Site Explorer, Keywords Explorer, SERP overview, Rank Tracker, Site Audit, Brand Radar, Web Analytics and your connected Search Console |
| Traffic data | Needs a separate Trends API plan | Included in the plan's data |
How I tested
I connected the Semrush MCP to an AI assistant with a Semrush account and asked the kind of questions I would ask on a normal workday. For each request, the Semrush MCP returns the number of API units it used, so I could log the real cost instead of estimating it.
The questions:
- "How does rankbuddy.io do in Google?" (domain overview for my own site)
- "Give me volume and difficulty for these 7 keywords" (a batch keyword lookup)
- "What are a competitor's top 10 keywords by traffic?" (organic keywords for chatseo.app)
- "What does that competitor's backlink profile look like?" (backlinks overview)
For Ahrefs I worked out what the same questions would cost from its published formula. That is an estimate, and I label it as one.
What a question actually costs on Semrush
Here is what the four requests used:
| Request | Rows returned | API units used |
|---|---|---|
| Domain overview for rankbuddy.io | 0 ("nothing found") | none reported |
| 7 keywords, volume and difficulty | 5 (2 had no data) | 50 |
| A competitor's top 10 organic keywords | 10 | 100 |
| A competitor's backlinks overview | 1 | 40 |
Two things stood out.
Cost scales with rows. The keyword and organic reports cost 10 units per row. Asking for a competitor's top 10 keywords cost 100 units; the same question for the top 100 would cost about 1,000. The assistant decides how many rows to request unless you tell it, so "show me everything they rank for" can eat a big part of a month in one go.
A new site gets nothing. Semrush had no data for rankbuddy.io in any regional database. Third-party indexes simply do not see a young site yet. If your own site is small, your own Search Console tells you more than either Semrush or Ahrefs, which is why I wrote a separate guide to Google Search Console MCP.
So a realistic research question that pulls three reports (some keywords, a competitor's top pages, a backlink summary) cost me about 190 units. With 50,000 units per billing period, that is roughly 260 questions before you need a unit package, and package upgrades are only sold with the higher Semrush plans.
If you divide the Starter price by its units, a 190-unit question works out to about $0.76. That is not how Semrush bills you, since the plan also includes the full Semrush app, but it is a useful way to compare.
What a question would cost on Ahrefs
Ahrefs publishes its formula: each request costs the larger of 50 units or rows × per-row cost, where the per-row cost is the sum of the fields you ask for. Most fields cost 1 unit, some cost 5 or 10. Requests served from Ahrefs' cache cost nothing.
Applied to the same questions (my estimate, not a test):
- Domain rating or a one-row overview: 50 units, the minimum.
- A competitor's top 10 keywords with 4 cheap fields: 10 × 4 = 40, so 50 units.
- The same for 100 keywords: 100 × 4 = 400 units, or more if you add a 10-unit field such as traffic.
- A small backlink summary: 50 units.
So the same three-report question lands somewhere between 150 and 500 units, depending on rows and fields. On Lite's 200,000 units, that is roughly 400 to 1,300 questions a month, far more headroom than Semrush's 50,000. Divided by the Lite price, it is roughly $0.10 to $0.32 per question.
The catch is the row cap. Lite returns at most 100 rows per request. That is fine for "top 10" questions and frustrating for "all keywords this site ranks for", which you have to page through. Standard raises it to 250 and Advanced to 500.
Setup: both take two minutes
Neither needs a config file or an API key in the normal case.
Semrush MCP in Claude: open Customize, then Connect your apps, find Semrush and sign in with your Semrush account. In a chat, mention @Semrush. In Claude Code it is one command: claude mcp add semrush ``https://mcp.semrush.com/v2/mcp`` -t http, then /mcp to sign in. Semrush also has official apps in ChatGPT and Perplexity, and config snippets for Cursor, VS Code and Gemini CLI.
Ahrefs MCP in Claude: add Ahrefs from Claude's connector directory and approve the consent screen, which creates an API key with MCP scope in your Ahrefs account. Ahrefs has setup guides for Claude, Claude Code, ChatGPT, Copilot Studio, Le Chat, n8n and more. One restriction worth knowing: Ahrefs says calling the MCP endpoint from custom scripts or standalone clients is not permitted; for code, use its REST API.
How the assistant talks to each server
This matters more than it sounds, because it affects speed and how often the assistant picks the wrong report.
Semrush uses three steps per report. The server exposes 12 "discovery" tools (domain overview, keyword research, backlinks and so on). Each one returns a list of reports; the assistant then asks for that report's parameters, and only then runs it. In my test every report took three calls, and the connector settings in Claude list 14 read-only Semrush tools in total. It keeps the tool list short, but every question needs more back-and-forth, and the assistant has to pick the right report name from lists like phrase_these, resource_organic and backlinks_overview.
Ahrefs exposes direct tools grouped into 20 categories, from Site Explorer and Keywords Explorer to Brand Radar, Web Analytics and Search Console. That is a lot of tool definitions for the assistant to read, so Ahrefs lets you choose which groups to load. Fewer steps per question, but a heavier tool list if you load everything.
Data: where each one is stronger
The MCP does not change the data. It is the same index you get in the app, so the usual Semrush vs Ahrefs trade-offs apply.
- Backlinks: backlinks are what Ahrefs is best known for, and its MCP brings the full backlink tools into the chat. Semrush's backlink reports are there too; if links are your main job, Ahrefs' index is the one it is known for.
- Keywords and PPC: Semrush has paid search and Google Shopping reports in its MCP, which Ahrefs does not focus on.
- Your own site: Ahrefs MCP includes a Search Console group and Web Analytics. Semrush reads your Position Tracking and Site Audit projects, but not Search Console.
- AI visibility: Ahrefs exposes Brand Radar reports. Semrush's AI visibility features sit in Semrush One and are not part of the MCP report list I saw.
- Traffic estimates: with Semrush, traffic and market data need a separate Trends API plan.
The vendors also disagree on simple numbers, which is worth remembering when an assistant quotes one with confidence. For "semrush mcp" and "ahrefs mcp", Semrush showed 260 searches a month each, while DataForSEO showed 390.
Limits that will bite you
- Units run out quietly. Neither assistant warns you before a large pull. Tell it how many rows you want ("top 20") or set a unit limit: Ahrefs lets admins cap monthly units per MCP key.
- Semrush top-ups need a bigger plan. On Starter you get 50,000 units and that is it; unit packages come with Semrush One Advanced or SEO Classic Business.
- Ahrefs Lite caps rows at 100. Large exports mean paging, and every page costs at least 50 units.
- Young sites are invisible. Both indexes may have little or nothing on a new domain. Use Search Console for your own site.
- Both are read-only in practice. They answer questions; they do not change your projects, your site or your rankings.
Which one should you use?
- You already pay for Semrush (Starter or higher): connect the Semrush MCP. Keep requests narrow and you will rarely hit 50,000 units.
- You already pay for Ahrefs (Lite or higher): connect the Ahrefs MCP, especially for backlink work. Plan around the 100-row cap on Lite.
- You pay for neither: I would not buy either one for the MCP alone. At $129 to $199 a month you are paying for a full SEO suite. If you want SEO data in Claude or ChatGPT without that, there are cheaper routes: DataForSEO's pay-as-you-go MCP for builders, or a hosted connector like RankBuddy's MCP (mine, from $29 a month), which combines your Search Console with keyword volumes, Google's top 10 and competitor gaps, but is not a full SEO suite like Semrush or Ahrefs.
If you want to look beyond these two, my roundup of the best SEO MCP servers compares ten of them, from SE Ranking and DataForSEO to Screaming Frog, with the real cost of one question.
If you are still choosing between the suites themselves, my comparisons of free Semrush alternatives and free Ahrefs alternatives cover what you lose with cheaper tools. For the bigger picture of chatbots, data connectors and agents, see my guide to SEO chat tools, and if you work in Claude, the Claude SEO page compares the main ways to give it SEO data.