Module web_mcp 

WebMCP - Browser-native agent tool discovery primitives.

Defines the core types for the Web Model Context Protocol (WebMCP), which enables browser-side AI agents to discover and execute tools exposed by web applications via the navigator.modelContext API.

Architecture

These are pure data types (no behavior) following the cellstate-core pattern. The API crate adds behavior (WebMcpConnector), the SDK wraps it in headless state machines, and the app dogfoods it via the SDK.

Relationship to MCP

Standard MCP operates server-to-agent (tools exposed by an MCP server). WebMCP operates browser-to-agent: web pages expose tools via navigator.modelContext.registerTool() that any connected agent (browser sidebar, desktop app, or programmatic client) can discover and execute. This module provides the type vocabulary for both sides.

Discovery Flow

┌────────────────────────────────────────────────────┐
│                WebMCP Discovery Lifecycle           │
│                                                    │
│  Page Load → Detect → Schema Parse → Ready         │
│     ↑                                  │           │
│     │          Execute ← Approve ← ─ ─┘           │
│     │             │                                │
│     └─── Context Update ←──┘                       │
└────────────────────────────────────────────────────┘

Structs

WebMcpAgentCapabilities

Capabilities an agent advertises to a WebMCP-enabled page.

WebMcpContext

Page context metadata exposed via WebMCP.

WebMcpDiscoveryState

Complete discovery state for a single page.

WebMcpInputSchema

JSON Schema for tool input parameters.

WebMcpManifest

WebMCP manifest for declarative (non-JS) tool exposure.

WebMcpPropertySchema

Schema for a single property within a tool’s input.

WebMcpSecurityPolicy

Security policy governing WebMCP tool access.

WebMcpTool

A tool exposed by a web page via WebMCP.

WebMcpToolAnnotations

Security and behavioral annotations for a WebMCP tool.

WebMcpToolCall

A request to execute a WebMCP tool.

WebMcpToolResult

Result of a WebMCP tool execution.

WebMcpUserContext

User identity context within a WebMCP session.

Enums

WebMcpDiscoveryPhase

State of the WebMCP discovery lifecycle for a single page.

WebMcpMemoryCapability

Memory capabilities an agent can provide to a WebMCP page.

WebMcpSandboxMode

Sandbox execution mode for WebMCP tools.