☯ HyperContext Standard v1.3.0 — Agentic Web Integration

What's New in v1.3.0

The DNA/RNA Architecture. HC pages now serve as both portable context documents (DNA) that any AI can read, AND executable tool servers (RNA) that browsers can register as WebMCP tools. One page. Two execution paths. Zero backend changes.

v1.3.0 introduces the Agentic Compliance Tier — an optional layer that transforms HC pages from documents AI reads into tools AI calls. This is achieved through a new hc-tools block and a lightweight WebMCP bridge script that registers tools with the browser's navigator.modelContext API.

Every v1.2.2 page is automatically v1.3.0 protocol-compliant. The agentic layer is purely additive.

Four Compliance Tiers

🔴

Protocol

MUST

🟡

Content

SHOULD

🟢

Agentic NEW

MAY

🔵

Discovery

MAY

Page Architecture

An HC v1.3.0 page consists of up to five blocks within a single HTML file:

hc-metadata application/json
Identity · Config

hc-instructions text/plain
Bootstrap · Context

hc-tools application/json
Tool Definitions

hc-human-docs HTML div
Documentation

bridge.js Runtime Script
WebMCP Registration

The `hc-tools` Block NEW

The hc-tools block is a JSON structure that defines tools the page exposes. It follows the same JSON Schema conventions as MCP tool definitions, ensuring compatibility across the entire MCP ecosystem.

Schema

<script type="application/json" id="hc-tools">
{
    "hc_tools_version": "1.0.0",
    "tool_prefix": "myapp",
    "tools": [
        {
            "name": "myapp_add_to_cart",
            "description": "Add a product to the shopping cart by product ID and quantity. Returns updated cart total.",
            "inputSchema": {
                "type": "object",
                "properties": {
                    "productId": { "type": "string", "description": "The product ID" },
                    "quantity":  { "type": "number", "description": "Number of items to add" }
                },
                "required": ["productId"]
            },
            "annotations": {
                "idempotentHint": false,
                "destructiveHint": false,
                "readOnlyHint": false
            },
            // DOM binding (optional — for declarative form-to-tool)
            "domBinding": {
                "selector": "#add-to-cart-form",
                "trigger": "submit"
            }
        }
    ]
}
</script>
        

Tool Definition Fields

Field	Required	Description
name	✅	Unique tool identifier. Use snake_case with domain prefix.
description	✅	Clear description for AI understanding. Use "Agentic SEO" — clear verbs, specific outcomes.
inputSchema	✅	JSON Schema draft-07 defining parameters.
annotations	Recommended	Hints for AI: idempotentHint, destructiveHint, readOnlyHint.
domBinding	Optional	CSS selector + trigger event for declarative form-to-tool mapping.
requiresConfirmation	Optional	Boolean. If true, runner MUST get user confirmation before executing.

The WebMCP Bridge Pattern

The bridge script reads the hc-tools block and registers each tool with the browser's navigator.modelContext API. This is the RNA transcription — converting static definitions into executable browser tools.

<script type="module">
// HC-WebMCP Bridge — reads hc-tools, registers with navigator.modelContext
(async function hcBridge() {
    // 1. Parse tool definitions from hc-tools block
    const toolsEl = document.getElementById('hc-tools');
    if (!toolsEl) return;
    const manifest = JSON.parse(toolsEl.textContent);

    // 2. Detect WebMCP runtime (native or polyfill)
    if (!navigator.modelContext?.registerTool) {
        console.log('[HC Bridge] No WebMCP runtime — tools available as static schema only');
        return;
    }

    // 3. Register each tool
    const registrations = [];
    for (const tool of manifest.tools) {
        const reg = navigator.modelContext.registerTool({
            name: tool.name,
            description: tool.description,
            inputSchema: tool.inputSchema,
            annotations: tool.annotations,
            async execute(args) {
                // Route to page-defined handler or DOM binding
                if (window.__hcToolHandlers?.[tool.name]) {
                    return window.__hcToolHandlers[tool.name](args);
                }
                // Fallback: DOM binding execution
                if (tool.domBinding) {
                    return executeDomBinding(tool.domBinding, args);
                }
                return { content: [{ type: 'text', text: `Tool ${tool.name} has no handler` }] };
            }
        });
        registrations.push(reg);
    }

    // 4. Lifecycle cleanup
    window.addEventListener('beforeunload', () => {
        registrations.forEach(r => r.unregister());
    });

    console.log(`[HC Bridge] Registered ${registrations.length} tools with WebMCP`);
})();
</script>
        

Execution Paths

The same HC page serves three distinct consumer types without modification:

Consumer	Reads	Execution	Auth
LLM Direct (URL paste)	hc-metadata + hc-instructions + hc-human-docs	Bootstrap reasoning context	None needed
HC Runner (CLI/extension)	All blocks including hc-tools schemas	Structured tool catalog + execution	Runner-managed
Browser Agent (WebMCP)	hc-tools → bridge → navigator.modelContext	Direct tool calls, no DOM scraping	Inherits browser session

Declarative Form-to-Tool Annotations

For pages with existing HTML forms, the domBinding field in hc-tools maps form submissions directly to tool invocations. The bridge script can also detect annotated forms:

<!-- Standard HTML form with HC tool annotations -->
<form id="checkout-form"
      data-hc-tool="myapp_checkout"
      data-hc-description="Complete the checkout process with shipping and payment details">

    <input name="address"
           data-hc-param-description="Full shipping address including city, state, zip"
           type="text" />

    <select name="shipping_method"
            data-hc-param-description="Shipping speed: standard (5-7 days), express (2-3 days), overnight">
        <option value="standard">Standard</option>
        <option value="express">Express</option>
    </select>

    <button type="submit">Place Order</button>
</form>
        

Agentic SEO. The data-hc-param-description attributes serve dual purpose: they help AI agents understand parameter semantics, and they improve the page's discoverability for agentic search systems. Write descriptions like meta-descriptions — clear verbs, specific outcomes, expected formats.

Security Model

Trust Boundaries

All v1.2.2 security rules carry forward. The agentic layer adds:

Rule	Enforcement
Tool execute() MUST NOT access cross-origin resources	Bridge script + browser CORS
Destructive tools MUST require user confirmation	annotations.destructiveHint + HITL
Tool registrations scoped to page lifecycle	beforeunload cleanup
Input validation before execution	JSON Schema validation in bridge
No credential leakage in tool responses	Content block sanitization

Human-in-the-Loop (HITL)

When requiresConfirmation: true or annotations.destructiveHint: true, the runner/browser MUST pause execution and present the pending action to the user before proceeding. This aligns with the W3C WebMCP proposal's yield-to-user mechanism.

Migration from v1.2.2

Zero breaking changes. Every valid v1.2.2 page is a valid v1.3.0 page. The upgrade path is purely additive: add hc-tools block, add bridge script, bump version number.

Step	Action	Breaking?
hc_version	Change "1.2.2" → "1.3.0" in hc-metadata	No
hc-tools	Add new script block with tool definitions	No (new block)
bridge.js	Add module script for WebMCP registration	No (new script)
agentic_capable	Add to execution config in hc-metadata	No (new field)
compliance_levels	Add "agentic": "optional" to metadata	No (new field)

Agentic Compliance Checklist

For pages targeting the Agentic tier (Tier 3), validate against these 8 items:

hc-tools block present with type="application/json" and id="hc-tools"
Each tool has name, description, and inputSchema at minimum
Tool names use snake_case with a domain prefix (e.g., myapp_action)
inputSchema follows JSON Schema draft-07 with type and properties
Destructive tools have annotations.destructiveHint = true
Bridge script checks for navigator.modelContext before registration
Tool registrations include beforeunload cleanup
execute() returns MCP-compatible content blocks: { content: [{ type, text }] }

Claude Code Feedback Loop

For development validation, connect Claude Code to the chrome-devtools-mcp server. This enables a closed-loop workflow:

1. Edit hc-tools definitions in your HTML file.
2. Bridge script auto-registers tools on page load.
3. Claude Code discovers tools via list_webmcp_tools.
4. Claude Code invokes tools via call_webmcp_tool.
5. Validate responses against HC compliance.
6. Iterate until all tools pass validation.

// Claude Code / claude_desktop_config.json
{
    "mcpServers": {
        "chrome-devtools": {
            "command": "npx",
            "args": ["@mcp-b/chrome-devtools-mcp@latest"]
        }
    }
}
        

Resources

Resource	URL
HC v1.3.0 Spec (this page)	https://hc-standard.org/spec/v1.3.0/
HC v1.2.2 Spec (previous)	https://hc-standard.org/spec/v1.2.2/
WebMCP W3C Explainer	https://github.com/webmachinelearning/webmcp
MCP-B Polyfill	https://www.npmjs.com/package/@mcp-b/global
Chrome DevTools MCP	https://github.com/WebMCP-org/chrome-devtools-quickstart
HC GitHub	https://github.com/hc-standard/hc-standard

☯ HyperContext Standard

What's New in v1.3.0

Four Compliance Tiers

Page Architecture

The hc-tools Block NEW

Schema

Tool Definition Fields

The WebMCP Bridge Pattern

Execution Paths

Declarative Form-to-Tool Annotations

Security Model

Trust Boundaries

Human-in-the-Loop (HITL)

Migration from v1.2.2

Agentic Compliance Checklist

Claude Code Feedback Loop

Resources

The `hc-tools` Block NEW