Sapling's free grammar, AI detection, and writing tools support WebMCP — an open browser standard that lets an AI agent call a page's tools directly instead of clicking around or scraping rendered text.
document.modelContext.registerTool({
name: 'check_grammar',
description: 'Checks English text for ' +
'grammar, spelling, and ' +
'punctuation errors.',
inputSchema: {
type: 'object',
properties: {
text: { type: 'string' },
},
required: ['text'],
},
execute: async ({ text }) => {
return await checkGrammar(text);
},
});WebMCP is a draft W3C Community Group standard that lets a web page expose callable tools to an AI agent that's browsing on a person's behalf — the in-page counterpart to the Model Context Protocol used by backend AI assistants. Where a scraping-based agent has to guess which button does what, a WebMCP tool gives it a named function with a description and a typed schema, the same way an API does.
A WebMCP-capable AI browser agent (Chrome/Edge, currently behind an origin trial) visits a Sapling tool page on your behalf.
Sapling registers a tool for that page's checker — a name, a description, and a plain-JSON input shape — right in the browser, no server round-trip beyond the page load.
The agent invokes the tool with your text and gets back structured results — edits, scores, entities — the same data the visible UI would show, without clicking through the page.
Every tool below is backed by the same free page a human visitor would use — click through to try it yourself, or point a WebMCP-capable agent at the URL.
Catch grammar, spelling, and punctuation issues, in English and several other languages.
More languages on the grammar checker page.
Detect AI-generated text, screen for unsafe content, and find or redact sensitive information.
Score, classify, and extract structure from text — sentiment, tone, readability, and more.
Paraphrase, reword, retarget tone or tense, split, summarize, and generate titles or acronyms.
Built into sapling.ai's own free tool pages. No install, no API key — a WebMCP-capable browser agent calls the tool the moment it loads the page. Best for an agent that's already browsing the web on your behalf.
An installable @saplingai/mcp-server package for Claude Desktop, Claude Code, Cursor, and other MCP clients. Requires a Sapling API key. Best for an AI assistant that isn't a web browser at all.
WebMCP is an emerging W3C Community Group standard (document.modelContext.registerTool()) that lets a web page register callable tools for an AI agent controlling the visitor's browser. Instead of an agent guessing which button to click or scraping rendered text, it calls the page's own tool directly and gets a structured result back.
As of 2026, WebMCP ships only behind an origin trial in Chromium-based browsers (Chrome and Edge). In every other browser, document.modelContext is undefined and Sapling's tool registration silently no-ops — the page works exactly as it does for a human visitor, with no errors and no extra requests.
The Sapling MCP Server (@saplingai/mcp-server) is an npm package any AI assistant — Claude Desktop, Claude Code, Cursor, and others — can install to call the Sapling API from a backend, with an API key. WebMCP is different: it requires no install and no API key. The tools are registered directly on sapling.ai's own free tool pages, so a WebMCP-capable browser agent visiting the site can use them immediately, the same way a human visitor would.
No. Each WebMCP tool calls the same free, public endpoint the page's own on-screen checker uses — there's no API key involved and no charge against any API plan. The usual fair-use rate limits on Sapling's free tools still apply.
No. A WebMCP tool call goes to the exact same Sapling API endpoint the page's visible checker already calls — it's a different entry point into the same request, not a new data path.
These agent-ready tools are a subset of everything Sapling offers for free, self-serve use.
Building your own application instead? Contact us about the Sapling API.