> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mcp-b.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# 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
`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](/explanation/architecture/transports-and-bridges)
and the [local relay reference](/packages/webmcp-local-relay/reference).