How Semrush MCP bills: units, per line
Semrush’s official MCP server is free to connect and billed in the same API units as the Semrush API. Each report has a published price per line returned, so a request for 100 rows costs 100 times the line rate. Semrush’s own developer documentation, on September 21, 2026:
| Report | Units | 100 rows cost |
|---|---|---|
| Domain overview | 10 per line | 1,000 |
| Domain organic keywords | 10 per line | 1,000 |
| Domain paid keywords | 20 per line | 2,000 |
| Keyword overview | 10 per line | 1,000 |
| Related keywords | 40 per line | 4,000 |
| Backlinks | 40 per line | 4,000 |
| Referring domains | 40 per line | 4,000 |
| Keyword difficulty | 50 per line | 5,000 |
Historical data costs five times the live rate. Qualifying plans include 50,000 MCP API units, refreshed on the renewal date. Semrush’s API help page says unused units expire rather than roll over.
The arithmetic: one question, two fifths of the month
Ask an assistant the question people actually ask: "compare us with our three closest competitors and tell me which keywords to go after." A careful agent answering that pulls, roughly:
- the top 100 organic keywords for each of three competitors: 3 × 1,000 = 3,000 units
- 100 backlinks for each, to judge how hard they are to catch: 3 × 4,000 = 12,000 units
- keyword difficulty on the 100 most promising terms: 5,000 units
That is 20,000 units, 40% of a month’s allowance, on one question, before any follow-up. Ask for historical data and the organic pulls cost five times as much. None of this is hidden: every rate is published. It is simply arithmetic nobody does until the balance hits zero.
The same 50,000 units buy 5,000 organic keyword rows, 1,250 backlink rows or 1,000 difficulty lookups a month. That is plenty for a person running focused reports and not much for an agent, because an agent asked an open question will make several calls before it answers, and each one bills per row.
Semrush API limits, and what running out looks like
There are two ceilings. The first is rate: no more than 10 requests a second from one IP address, or 10 simultaneous requests per user, which an assistant will rarely hit. The second is the balance, and that is the one you will meet.
When it runs out, the SEO API answers with ERROR 132, and the Projects API with HTTP 403. The quieter failure is the partial one: a report priced per line returns only as many rows as your balance covers instead of failing. In a chat window the assistant presents whatever came back, and nothing tells you that the list of 100 keywords was cut to 30 because the balance ran low.
Plan eligibility is the other surprise. MCP access comes with Starter and Pro+ (and the legacy SEO Classic Pro and Guru plans). The entry SEO plan does not qualify, and Advanced, at $549 a month, includes no MCP units: it needs a separately purchased package. The more expensive plan comes with fewer MCP units. The full plan ladder is in Semrush pricing, explained.
The alternatives, by what you are actually trying to fix
If you want different data, not a different meter: Ahrefs MCP. Ahrefs runs a remote MCP server on Lite ($129 a month) and above. It is metered too: every call costs at least 50 units, drawn from the same pool as the Ahrefs API, and extra units are sold only on Enterprise. The allowance is larger than Semrush’s, and Ahrefs’ own pages disagree on how much larger.
If you only need your own rankings: a Search Console server. Google ships no official one, but community servers read the Search Console API for nothing. They see what you rank for and nothing about competitors. The options are in the best MCP servers for SEO.
If the meter is the problem, and the agent should do the work: Sprites. Sprites is an AI marketing agent with its own SEO MCP server. It gives Claude or ChatGPT keyword volume, difficulty and intent, and your own Search Console, behind one endpoint, with no API units and no separate API plan. The connector comes with every paid plan and runs on the plan’s monthly credits, from $66 a month billed yearly. It also acts on the answer: a page edit arrives as a diff you approve, and on Launch and up the post it recommends lands in your CMS as a draft. What it does not have is Semrush’s depth on a competitor’s paid search history or shopping ads. For that, Semrush is still the stronger source.
Who should use which
Keep Semrush MCP if you already pay for Starter or Pro+, a person is driving the questions, and you want the deepest competitor dataset. Ask narrow questions ("top 50 organic keywords in the US") rather than open ones, and check the unit balance weekly for the first month.
Use Ahrefs MCP if backlinks are the job and you are on Ahrefs already. Budget for the 50-unit floor on every call.
Use Sprites if you want the agent to go from question to published fix without watching a unit balance: keyword research, the page fix, the internal links and the Search Console follow-up from $66 a month billed yearly, and the post itself on Launch.
Use both if competitor research is a weekly habit: Semrush for the market view, Sprites for your own site. Every connected server adds tool descriptions the model reads on every turn, so stop at two or three.