Stagewise is built for one specific moment: a developer running Cursor, Claude Code, or another AI coding agent against a local dev server, who wants to click the element that looks wrong instead of typing "the button in the top nav, the blue one, third from the left." The browser toolbar captures the element's selector, computed styles, and component hierarchy, and hands that structured context straight to the agent. The core toolbar is open source under AGPLv3 and runs entirely inside your local project with no account required; stagewise also sells paid cloud plans on top of it, as of August 2026.
That scope is deliberate, and narrow. Stagewise assumes one person, one machine, one app running on localhost. There's no share link, no way for a designer or a client to open the same session from their own browser, and nothing that keeps a record of what was flagged once the agent has consumed the prompt and moved on.
MarkLayer solves a related but different problem. Its core loop is human-to-human: someone opens a live URL, a client's staging build, a teammate's production site, nothing to install, and leaves a comment, a drawing, or a voice note that a whole team can see and thread through, with statuses that update in real time. The MCP server sits on top of that same room rather than existing as a separate product, so an agent can watch for new annotations, mark one in progress, and resolve it with a reply the human reviewer sees update live. Pointing an agent at one element and pointing a team at a whole page are not the same job, even though the underlying idea, give the agent something more precise than English, is shared.
Where the two genuinely overlap is narrow. A solo developer who wants element-level context in an editor agent and doesn't care about a review room at all is better served by stagewise, or by the lighter localhost-only tools below. What follows are four ways to get UI-element context to an agent, from the narrowest (a debugging-only MCP server) to the widest (a shared room anyone can join).
MarkLayer is the alternative that takes element-to-agent handoff beyond localhost: any URL, share links non-developers can open, and an MCP loop where the agent resolves annotations in a live room. Agentation and Vibe Annotations are lighter localhost-only options. Chrome DevTools MCP is the debugging-focused adjacent, not an annotation tool.
| Option | Price | Best for |
|---|---|---|
| MarkLayer | Free. No tiers, no seats | Element-to-agent handoff when designers, PMs, or clients are part of the loop. |
| Agentation | Not tracked | React developers who want the toolbar inside the app they're building. |
| Vibe Annotations | Not tracked | A minimal, local-only capture-and-prompt workflow. |
| Chrome DevTools MCP | Not tracked | Giving an agent browser-level debugging power alongside any annotation tool. |
Free and open-source under Apache-2.0, and built around a shared room rather than a single prompt. Paste any URL, staging, production, a client's site, and nothing to install, or use the Chrome extension for localhost; annotations, live cursors, and voice all sync into that same room. The MCP server gives the agent a two-way loop: watch for new comments, acknowledge one, resolve it with a summary, or dismiss it with a reason, and every status change shows up live for whoever else is in the room.
An npm dev-dependency you add to your own React app, so the annotation toolbar ships inside the app you're building rather than as a separate extension. Clicking an element exports its selector, component hierarchy, and computed styles, and its MCP package lets the agent talk back rather than only receive a one-shot prompt. Free for individual use, with paid licensing once a team wants to share it.
A free Chrome extension built for one narrow job: click an element on localhost and get a structured prompt formatted for Claude Code, Cursor, or another agent. It runs its own local MCP server, so nothing leaves your machine and no account is needed. There's no room, no sharing, and no history beyond the current session, by design.
Google's official MCP server, and not an annotation tool at all; nobody points at an element here. It gives an agent direct DevTools access instead: console output, network requests, performance traces, and the ability to drive the page itself. It pairs naturally with any of the three above, since none of them hand an agent runtime debugging state on their own.
Paste any URL at marklayer.app and annotate the live page in your browser. No install, no account, no sign-up. Recipients of your share links don't need to install anything either.
Annotate a page