WebMCP and PlugMCP Browser
Sites register tools in the page. Browser runs them in your tab. Hosted MCP stays on the gateway.
WebMCP is how a website names its own actions. A page calls document.modelContext.registerTool so an agent can discover what the site already knows how to do.
PlugMCP Browser (Usher) is the local door: a Chrome or Edge extension plus a stdio MCP server. Consent stays in the tab. Paying, sending, or deleting waits for Allow.
Hosted servers on mcp.plugmcp.ai are a different cable. They wrap APIs and remote MCP URLs that you bring into the app. They never see your browser cookies. Do not proxy tab tools through Railway or n8n.
Install from /browser. Point Cursor at the local usher-mcp.js. The directory listing plugmcp-browser is this product, marked local.