AI agents call a11y_check_pattern to retrieve information from A11y without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a read-only analysis tool. It accepts HTML input, performs static code analysis, and returns diagnostic information and suggestions. There are no side effects, no state changes, no execution of arbitrary code, and no data modification. The worst outcome of misuse would be receiving irrelevant or false-positive accessibility findings, which poses minimal risk.
From the tool's definition The tool 'a11y_check_pattern' analyzes HTML code snippets and returns issues with WCAG references and fix suggestions.
Attacks that exploit this kind of access
Analyze HTML code snippet for common accessibility issues. Returns list of issues with WCAG references and fix suggestions. It is categorised as a Read tool in the A11y MCP Server, which means it retrieves data without modifying state.
Register the A11y MCP server in PolicyLayer and add a rule for a11y_check_pattern: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches A11y. Nothing to install.
a11y_check_pattern is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the a11y_check_pattern rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for a11y_check_pattern. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
a11y_check_pattern is provided by the A11y MCP server (shawnmcb/a11y-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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