WebMCP — Web Model Context Protocol

Browser-native WebMCP registers tools on the page via navigator.modelContext (or document.modelContext). Enabling the domain mounts discovery URLs; you still must register tools and include a template tag for in-browser use.

Checklist after ENABLED

1. WEBMCP.ENABLED = True in APP_CONFIG["agentweb"].
2. Include agentweb.urls (already done in getting started).
3. Register tools in Python (agentweb.webmcp.tools).
4. Add {% webmcp_register %} to the base template (usually before </body>).
5. Optionally enable Discovery middleware for Permissions-Policy: tools=(self).
6. Leave REMOTE_BRIDGE False unless you accept the headless HTTP trust model.

APP_CONFIG = {
    "agentweb": {
        "WEBMCP": {
            "ENABLED": True,
            "DATA_SOURCE": "proxy",   # reserved (not enforced yet); keep proxy
            "REMOTE_BRIDGE": False, # HTTP invoke for headless agents
        },
    },
}

Install the proxy extra when you later wire server-side vendor calls (the DATA_SOURCE key is reserved for that posture and is not enforced yet):

pip install "django-agentweb[webmcp]"

URLs

URL	Name	Role
/.well-known/webmcp.json	agentweb-webmcp-manifest	JSON tool descriptors (not the browser API itself)
/webmcp/tools/<name>	agentweb-webmcp-tool	Optional remote bridge (POST); 404 unless REMOTE_BRIDGE

Template tags

Browser registration

{% load agentweb_webmcp %}
{% webmcp_register %}

Renders nothing when WebMCP is disabled. When enabled, embeds tool descriptors and loads agentweb/webmcp.js, which registers tools when the browser API is present (progressive enhancement).

Declarative form attributes

{% load agentweb_webmcp_decl %}
<form {% webmcp_form_attrs "search_rooms" "Search available rooms" %}>
  ...
</form>

Emits data-mcp-tool-* attributes for agents that understand declarative markup.

Permissions-Policy without Discovery middleware

If you enable WebMCP but skip Discovery middleware, you can still advertise same-origin tools permission:

{% load agentweb_webmcp_decl %}
<meta http-equiv="Permissions-Policy" content="{% permissions_policy_tools %}">

Prefer Discovery middleware when that domain is on — it sets the response header automatically when WebMCP is enabled.

Register tools

from agentweb.webmcp import tools

@tools.register(
    name="check_availability",
    description="Check room availability for dates.",
    read_only_hint=True,
    input_schema={"type": "object", "properties": {"check_in": {"type": "string"}}},
)
def check_availability(request, **params):
    return {"available": True, "check_in": params.get("check_in")}

Conventions:

• Prefer read-only tools (read_only_hint=True).
• State-changing tools should set requires_human_confirmation=True.
• Never expose secrets or privileged admin actions as tools.

Remote bridge (optional)

REMOTE_BRIDGE: True allows CSRF-exempt POST /webmcp/tools/<name> for headless agents. Read-only tools execute; confirmation-required tools return 409. This is not a substitute for in-browser WebMCP — see Security.

Verify

1. Open a page that includes {% webmcp_register %}.
2. GET /.well-known/webmcp.json lists your tools.
3. With bridge off, POST /webmcp/tools/... returns bridge-disabled.

See Configuration.