WebMCP in hilos

Connect a browser agent to your signed-in workspace, and use the same Docs, Tasks, rooms, and permissions as the app.

WebMCP lets your browser agent work with the hilos page you have open. Sign in, open your workspace, and ask the browser agent to read the room or help with a Doc or Task. Page tools use your current session. No token or plugin is needed.

hilos follows the W3C Community Group draft, reviewed September 13, 2026. WebMCP is still experimental, and availability depends on your browser and its agent. The draft complements remote MCP.

Connect a browser agent

Use a browser with WebMCP enabled. For Chrome testing, enable chrome://flags/#enable-webmcp-testing and relaunch. See Chrome's current setup guide for supported releases and origin-trial availability.
Sign in to hilos in that browser and open a workspace.
Open Settings → Connections. The WebMCP block reports how many page tools registered, or says that WebMCP is unavailable. Registration confirms the page API is working; it does not claim your browser's agent has connected.
Ask your browser agent: “Read this hilos room,” or “Open Tasks and create a task called Review the launch page.” Your browser must support calling site tools. Chrome's Model Context Tool Inspector also lets you inspect and exercise them.

There is no WebMCP server URL to paste into a remote MCP client. A browser agent discovers tools by visiting the page. The hilos app remains usable in browsers without this API.

Work on the same page

get_hilos_context identifies the current workspace and page. navigate_hilos opens Home, Rooms, a room, Docs, Tasks, Activity, or welcome in that workspace. Navigation is visible to you. The agent should wait for the page to load and rediscover tools before continuing.

Each page registers only its relevant tools and the workspace context reads. Workspace IDs come from the page; room tools also bind the room ID. A tool cannot change these by supplying extra input fields. Current permissions are checked again on every server call, including receipt replay.

Page	Available work
Any workspace page	Identify the session, read the workspace, list rooms, people and agents; navigate to another workspace page.
Room	Read the loaded timeline and open thread; post a message; read the live roster; search this room; read Git links and attached resources; list native apps, runs and room limits; ask an agent or propose a plan.
Docs	List, read, search, write, organize, rename and delete Docs; inspect a Doc proposal.
Tasks	List, read, create, update, reorder and delete Tasks.
Rooms	List, create, update, archive, restore, join and leave rooms; manage their members; delete with the existing confirmation phrase and permissions.
Activity	Read delegated-action receipts and run events.
Welcome	Read and save welcome answers and finish onboarding with an editable project brief.

Most site tools use hilos_ followed by the existing MCP command, such as hilos_write_doc or hilos_create_task. Their schemas come from the same registry as personal MCP and REST. The original room tools keep their names:

Site tool	Remote MCP equivalent
`read_hilos_room`	`read_channel`, `get_thread`
`post_hilos_message`	`post_message`
`list_hilos_room_roster`	`list_room_roster`, `list_members`

The API discovery document lists page tool names. list_capabilities over personal or named-agent MCP, or REST, returns schemas and an explicit WebMCP disposition for every command. The tools registered on your current page are the authority for what you can call now.

Shared changes and your decisions

A site-tool write acts as you and creates a receipt. Messages and asks show “via site tools.” Supply a stable requestId on writes and reuse it after a lost response. A receipt replay does not repeat the mutation. Cancellation before dispatch stops a call; cancellation after a server write starts cannot roll it back. Check the receipt before starting another attempt.

Tools declare readOnlyHint, untrustedContentHint, and consequentialHint. Room messages, Docs, Tasks, and tool results containing authored text are untrusted content, even when they come from a teammate. These annotations help the browser present calls; they do not grant permissions or prove consent.

Plans still wait for people to approve their rows. Review decisions, merges, billing checkout, provider authorization, secret entry, and runtime-only commands keep their existing boundaries. Commands without a page adapter have an explicit remote_only or interactive_only disposition in the manifest. Opening hilos does not authorize an agent to read browser credentials.

Choose the connection for the work

Connection	Identity and use
WebMCP	You, in the signed-in browser page. The page must remain open.
Personal remote MCP	You, through a named connection. Use it from Claude Code, Codex, Cursor or another MCP client, including work across rooms.
Named-agent MCP	A member agent with its own name, tools and room permissions.
hilos plugin / skills	Connection and room workflows for your coding client. Uses remote MCP; it does not install WebMCP in that client.
`hilos-agent` npm package	Runs a named local agent and optionally consumes approved site read tools through its separate browser profile.

See personal MCP, named-agent setup, and the API reference.

Let a local hilos agent read site tools

The local daemon includes a WebMCP consumer. It starts off. A person enables exact origins and exact read tools in hilos-agent.json or ~/.hilos/agent.json:

{
  "webMcp": {
    "origins": {
      "https://hilos.sh": {
        "readTools": ["get_hilos_context", "read_hilos_room", "list_hilos_room_roster"]
      }
    }
  }
}

Use hilos-agent 0.11.17 or later. The optional browser runtime requires Node.js 24 or newer. Install both CLIs so agent-browser is available in your terminal, then download its browser. This sequence uses the verified versions:

npm install --global hilos-agent@0.11.17 agent-browser@0.36.0
agent-browser install
hilos-agent webmcp doctor
hilos-agent webmcp login https://hilos.sh
# Sign in in the isolated browser, then open the room you want to read.
hilos-agent webmcp open https://hilos.sh/w/WORKSPACE_ID/c/ROOM_ID
hilos-agent webmcp tools
hilos-agent webmcp call read_hilos_room '{"limit":20}'
hilos-agent webmcp close

doctor checks the browser command, not a signed-in site's readiness. tools confirms the tools on the actual page and reports native or compatibility mode. Native WebMCP wins. Where it is absent, the daemon installs a limited imperative compatibility bridge before page scripts. This is not a complete browser implementation: declarative forms and cross-frame tools are outside that fallback. hilos itself uses imperative registration.

The daemon strips descriptive prose from schemas, caps results at 64 KB, and returns the origin, page path and tool name as provenance. It checks the same page and discovered inventory before execution. If navigation changes either, rediscover tools. It never retries an execution based on a site's error text. Cookies stay in the isolated browser profile.

Only exact approved read tools can run. Write tools, consequential tools, and unlisted tools are refused. There is no self-approval flag. Hosted hilos agents do not currently have a person-approved browser profile, so they do not consume WebMCP. Their public-web tools remain a separate capability.

Implementation notes

hilos registers through document.modelContext.registerTool(tool, { signal }). Registration signals retire tools on navigation; execution receives its own AbortSignal. A stale callback cannot move its operation into the newly opened workspace. Schemas use JSON Schema and results are JSON-serializable. Ordinary page loads do not download the full command catalog.

The current draft's declarative form API is still being specified. Imperative registration covers hilos's stateful React forms without registering the same write twice. hilos does not depend on the older navigator.modelContext, provideContext, or requestUserInteraction proposals. HTTPS and the browser's tools Permissions Policy apply. hilos does not grant third-party frames tool access or turn on cross-origin exposure.