document.modelContext. Execution stays inside the page and can reuse its
origin, authenticated session, application state, and user-visible workflow.
This makes WebMCP a better fit for operations that belong to an active site.
Server-side MCP remains the better fit for capabilities that must exist
independently of a browsing context.
The models can still meet at the transport layer. MCP-B transports, the local
relay, and the Chrome DevTools bridge expose page-hosted WebMCP tools to
external MCP clients without moving execution out of the site.
See Transports and bridges
and the local relay reference.Explanation
WebMCP vs MCP
Why browser-hosted WebMCP tools and general MCP servers use different runtime and trust boundaries.
MCP connects an agent to capabilities exposed by a local process or remote
service. That server owns its deployment, credentials, transport, and
authorization model independently of any browser tab.
WebMCP publishes capabilities from the current website through
