# AI writing tools with a public API and MCP server, by plan · ScriptGrain

> Fourteen AI writing tools checked for a public REST API and an MCP server, the plan each needs, how they authenticate and what an assistant can actually call, with the date each was read.

Canonical: https://scriptgrain.com/reference/api-mcp-access-matrix

# Which AI writing tools have a public API and an MCP server: access by plan

*By Jack Stovell · published 2026-09-21 · checked 2026-09-20*

Fourteen AI writing tools were checked for a public API and an MCP server. Seven run an MCP server (ScriptGrain, VoiceMoat, ContentIn, Taplio, Jasper, Typeface, Pressmaster). Four document a public API (ScriptGrain, Jasper, Writer, Acrolinx). On most, access sits behind a Pro, Business or Enterprise plan. ScriptGrain's are on every plan including Free.

## How access was checked

So here's the thing: "checked" means something specific. Each vendor's own pages were read on the date given, pricing pages, docs, comparison tables, the lot. Where a page stated a fact plainly, that's what got recorded. Where nothing was stated, it's marked "not published", the vendor simply never said. Where the harvest of a site turned up no such page at all, that's "not found", a different situation, and worth keeping separate.

That distinction matters more than it sounds. Writer documents an API but no MCP page was found on its site. Acrolinx documents an API too, and again, no MCP page turned up. Copy.ai has no MCP found across 1,157 pages and, oddly, 0% FAQ schema on the same set. None of that means these tools definitely lack the feature; it means the public page trail doesn't show it as of the check date. Fair enough, but it's the only honest way to report this.

## The access matrix

The table below lines up all fourteen tools against API presence, MCP presence and the plan tier each requires. A few patterns jump out once you see it laid flat.

MCP servers cluster at the higher end of pricing almost everywhere except one. VoiceMoat's MCP needs Pro at $69 a month; Creator, at $35, does not include it. Taplio's MCP sits at mcp.taplio.com with no free plan at all, just a 7-day trial ahead of $39, $69 or $199 a month. Jasper's MCP lives at jasper.ai/mcp, paired with a Business plan that's custom-priced. Typeface offers an MCP server with OAuth 2.1, but you have to contact sales to find out what tier unlocks it. Pressmaster bundles MCP for Claude into its Pro plan at $72.

ScriptGrain is the outlier. API and MCP both, on every plan including Free. Writer costs £12 a month, Studio is £99 for 10 profiles and 3 seats, Agency is £299 unlimited profiles and 10 seats. No tier gate on the technical access itself.

Tool · Public REST API · Plan required for the API · MCP server · Plan required for MCP · Auth · What an assistant can do with it
ScriptGrain · Yes, documented at /docs/api · Every plan including Free · Yes, mcp.scriptgrain.com/mcp, 30 tools · Every plan including Free · Bearer key or OAuth (dynamic registration) · Build a profile, draft in it, score any text, compare pieces, polish, humanize, detect, monitor, memory
VoiceMoat · Not published · n/a · Yes, voicemoat.com/mcp, 15 tools · Pro ($69) and up · Account token · Read the trained voice, draft, score 0 to 100, schedule and post to X and LinkedIn
Jasper · Yes, jasper.ai/api · Business · Yes, jasper.ai/mcp · Not stated on the page · API key · Brand guardrails and generation inside other tools
Typeface · Not published · n/a · Yes, typeface.ai/mcp · Enterprise · OAuth 2.1 · Brand-kit grounded generation in Claude, ChatGPT, VS Code
Taplio · Not published · n/a · Yes, mcp.taplio.com · Paid plans (no free plan) · Account · Draft, schedule and publish LinkedIn posts
ContentIn · Not published · n/a · Yes, LinkedIn MCP server · Pro ($59) · API key, scoped per profile · Draft, schedule, publish and read LinkedIn analytics
Pressmaster · Not published · n/a · Yes, pressmaster.ai/mcp · Trial and paid · Account · Turn conversations into articles and posts
Writer · Yes, API documentation · Enterprise · Not found in the harvest · n/a · API key · Generation and workflows
Acrolinx · Yes, API documentation · Enterprise · Not found · n/a · API key · Content scoring against style guides
Copy.ai · Not published · n/a · Not found (glossary and blog only) · n/a · n/a · n/a
Noren · No · n/a · No · n/a · n/a · Profile is a Markdown file you paste into any LLM
DoppelWriter · No · n/a · No · n/a · n/a · n/a
Grammarly · Text editor SDK only · n/a · No · n/a · n/a · n/a
HyperWrite · No · n/a · No · n/a · n/a · n/a

## Public APIs

Four vendors document a public API: ScriptGrain, Jasper, Writer, Acrolinx. That's it from the fourteen checked.

ScriptGrain's sits at a REST base (auth.scriptgrain.com/functions/v1/api-v1), authenticated with a bearer key starting sg_live_, generated from Settings then API. It's live on every plan including Free, with rate limits of 60 requests a minute per key, 5 profile extractions an hour, 200 voice-match scores an hour and 3 brand mimics an hour. Full detail on that lives at [/ai-writing-api-and-mcp-server](https://scriptgrain.com/ai-writing-api-and-mcp-server).

Jasper's API sits behind Business, which is custom-priced rather than published as a flat number. Writer documents its API too, gated to Enterprise, also custom. Acrolinx documents an API but the whole product is request-a-demo, so there's no self-serve number to quote at all.

Ten of the fourteen tools have no documented public API. Noren offers a Markdown profile you paste into any LLM instead, which is a different mechanism entirely, not an API in the sense used here. VoiceMoat's API access is not published. ContentIn, DoppelWriter, Copy.ai, Typeface, Pressmaster, HyperWrite: none show a public API page.

## MCP servers

Seven of the fourteen. Here's the full list, named, with the plan each requires.

ScriptGrain runs its MCP at mcp.scriptgrain.com/mcp, streamable HTTP with legacy SSE at /sse, 30 tools, every plan including Free. VoiceMoat's MCP (15 tools) needs Pro at $69 a month or above. ContentIn bundles a LinkedIn MCP server into its Pro plan at $59. Taplio's lives at mcp.taplio.com, accessible from its cheapest paid tier since there's no free plan to begin with. Jasper's sits at jasper.ai/mcp under Business. Typeface has one with OAuth 2.1, tier unpublished. Pressmaster's is built for Claude, included on Pro at $72.

The seven without an MCP server found: Writer, Acrolinx, Copy.ai, Noren, DoppelWriter, Grammarly and HyperWrite. Not found doesn't mean ruled out; it means the page trail doesn't show one.

Worth a beat on setup, since this is where "an MCP server exists" and "you can actually use it" diverge. ScriptGrain's connects through Claude Code with a single command, through claude.ai via Settings, Connectors, Add custom connector, through ChatGPT the same way where the plan allows, and through Gemini CLI via a settings.json entry with the bearer header inline. Cursor and other clients just need the URL plus that header. A general rundown of how these connectors work across clients sits at [/works-with/claude](https://scriptgrain.com/works-with/claude) and [/works-with/chatgpt](https://scriptgrain.com/works-with/chatgpt); a fuller glossary of MCP terminology is at [/reference/mcp-tool-reference](https://scriptgrain.com/reference/mcp-tool-reference).

## Scoring versus drafting: what the tools expose

Most MCP servers draft and publish. That's the job: generate a piece, push it somewhere, done. Two go further and expose a voice score. VoiceMoat scores 0 to 100. ScriptGrain scores 0 to 1, with deltas per feature attached to every score.

Only one of those two publishes the method behind the number. VoiceMoat's score has no published method anywhere on its 100 pages, no named author either. You get the number, not the reasoning. ScriptGrain publishes its method at [/reference/voice-measurement-framework](https://scriptgrain.com/reference/voice-measurement-framework), scoring every draft across 45 attributes.

That gap runs wider across the category than just these two. Across the full 2026-09-20 harvest, 61 tools and 14,792 pages with 13,581 classified, not one competitor page publishes a scoring method for voice, an attribute list, or before-and-after numbers on a single brief. Anyword has a score, but it's a performance-prediction score, not a voice one, so it's a different animal entirely. Rytr's My Voice page runs 173 words. HyperWrite's style tool pages sit at 582 to 652 words, no date, no author, no schema. Thin pages, thin claims.

Full comparison across the tools sits at [/reference/ai-writing-voice-tools-matrix](https://scriptgrain.com/reference/ai-writing-voice-tools-matrix); the mechanics behind ScriptGrain's own score are at [/reference/brand-voice-api](https://scriptgrain.com/reference/brand-voice-api).

## What API access costs

ScriptGrain's rate limits are generous but not infinite: 60 requests a minute, 5 profile extractions an hour, 200 voice-match scores an hour, 3 brand mimics an hour. And here's the part people miss: API generations draw on the same credits as the app. There's no separate API budget sitting off to the side. One credit per variant on a generation call, deducted after delivery, with an Idempotency-Key header so a retry doesn't double-charge you.

Jasper's API access requires Business, custom-priced, no published flat rate. Writer's requires Enterprise, also custom. Neither vendor publishes a self-serve number for API-specific pricing; you go through sales.

That's a real difference in shape, not just price. One system meters by request and by credit inside a plan you can see the number for. The other two gate the whole capability behind a conversation with a sales rep. Both are legitimate ways to run a business. Only one lets you check the maths yourself.

## Limits

"Not found" means the harvested site carried no API or MCP page, which is not proof the feature does not exist behind a login or a sales conversation. Plan requirements were read from public pages on the dates given and may have moved. What a tool exposes over MCP was read from its tool list, not exercised end to end, except ScriptGrain\'s own.

## Questions

### Does every AI writing tool with an MCP server also have a public API?

No. Of the seven with an MCP server, only two (ScriptGrain and Jasper) also document a public API. Writer and Acrolinx document an API with no MCP page found, and VoiceMoat, ContentIn, Taplio, Typeface and Pressmaster run MCP servers with no published API alongside them.

### Is VoiceMoat's MCP server available on its cheapest paid plan?

No. VoiceMoat's MCP needs Pro at $69 a month. Creator, at $35, does not include it. Only Free sits below Creator, and Free obviously doesn't unlock MCP tools either, so Pro is the actual floor.

### What does "not published" mean versus "not found" on this page?

"Not published" means the vendor's own page existed but didn't state the fact, so it's a gap in disclosure. "Not found" means the site harvest turned up no relevant page at all. They're different failures: one is silence on a page you can see, the other is an absent page.

### Which tools publish how their voice score actually works?

Only ScriptGrain does, at /reference/voice-measurement-framework, scoring drafts 0 to 1 across 45 attributes. VoiceMoat publishes a 0 to 100 score with no method behind it. Across the wider 61-tool harvest, no competitor page publishes a scoring method, an attribute list, or before-and-after numbers.

### Do API calls cost extra on top of a ScriptGrain subscription?

No separate budget exists. API generations draw on the same credit pool as the app itself, one credit per variant, deducted after delivery. Free-tier accounts get the same API access as paid tiers, just with the same rate limits and credit allowance that apply across the board.

## Methodology

Each row was read from the vendor's own API or MCP page in the 2026-09-20 harvest (61 tools, 14,792 pages) or the dated /vs verification. 'Not found' means the harvested site carried no such page; 'not published' means the page did not state a plan. Re-checked monthly.

## Sources

- [VoiceMoat MCP](https://voicemoat.com/mcp)
- [Jasper MCP](https://www.jasper.ai/mcp)
- [Jasper API](https://www.jasper.ai/api)
- [Typeface MCP](https://www.typeface.ai/mcp)
- [Pressmaster MCP](https://www.pressmaster.ai/mcp)
- [ContentIn: LinkedIn MCP](https://contentin.io/glossary/linkedin-mcp/)
- [ScriptGrain MCP documentation](https://scriptgrain.com/docs/mcp)
- [ScriptGrain: Writing voice can be measured (the 45 attributes)](https://scriptgrain.com/writing-voice)
- [ScriptGrain API reference (v1)](https://scriptgrain.com/docs/api)
- [ScriptGrain research index (SGR studies)](https://scriptgrain.com/research)