# get_apg_pattern

ENTRY POINT for building a composite component. Returns the verbatim W3C APG card (about, keyboard interactions, examples), the ARIA contract for its roles, the native HTML elements that carry them, and suggested_queries (ACT searches) to run next. Also returns applicable_scs: the WCAG criteria that apply from the component's structure alone (the floor) at the chosen level, plus a tiered verification checklist (axe / agent / human) and a count of further criteria that depend on the content you add. For native primitives (text input, link, image) use get_aria_role instead.

Agent View of the PolicyLayer registry record for `get_apg_pattern`. HTML page: https://policylayer.com/tools/a11y-assist-mcp/get-apg-pattern

## Facts

- Tool: `get_apg_pattern`
- Server: A11y Assist (`a11y-assist-mcp`) — https://policylayer.com/tools/a11y-assist-mcp.md
- Install: `npx -y a11y-assist-mcp`
- Homepage: https://www.npmjs.com/package/a11y-assist-mcp
- Risk category: Read (Low risk)
- Registry record: grade D, identity unverified
- Server rate-limited: no
- Parameters: 2 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `name` | string | yes | APG pattern name — e.g. dialog, tabs, combobox, accordion, listbox, disclosure, menubutton. Aliases like "modal" → dialog are accepted. Call list_apg_patterns t |
| `level` | string | no | Target WCAG conformance level (cumulative). Stamped into the suggested ACT queries. |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "get_apg_pattern",
    "arguments": {
      "name": "<name>"
    }
  }
}
```

## Why get_apg_pattern is rated Low

Even though get_apg_pattern only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.

## Use case

AI agents call get_apg_pattern to retrieve information from A11y Assist without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches A11y Assist:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "get_apg_pattern": {}
  }
}
```

## Other tools on A11y Assist (11)

- `audit_html` — Execute — https://policylayer.com/tools/a11y-assist-mcp/audit-html.md
- `audit_url` — Execute — https://policylayer.com/tools/a11y-assist-mcp/audit-url.md
- `evaluate_verification` — Read — https://policylayer.com/tools/a11y-assist-mcp/evaluate-verification.md
- `get_act_rule` — Read — https://policylayer.com/tools/a11y-assist-mcp/get-act-rule.md
- `get_aria_role` — Read — https://policylayer.com/tools/a11y-assist-mcp/get-aria-role.md
- `get_element_roles` — Read — https://policylayer.com/tools/a11y-assist-mcp/get-element-roles.md
- `get_wcag_sc` — Read — https://policylayer.com/tools/a11y-assist-mcp/get-wcag-sc.md
- `list_apg_patterns` — Read — https://policylayer.com/tools/a11y-assist-mcp/list-apg-patterns.md
- `search_act` — Read — https://policylayer.com/tools/a11y-assist-mcp/search-act.md
- `search_wcag` — Read — https://policylayer.com/tools/a11y-assist-mcp/search-wcag.md
- `evaluate_applicability` — Write — https://policylayer.com/tools/a11y-assist-mcp/evaluate-applicability.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=a11y-assist-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/a11y-assist-mcp