Pre-flight check on html / css / js BEFORE writing via update_html. Returns { ok, errors, warnings, parsed } where parsed has byte counts per field and dropped (true if the sanitizer would strip anything from html). Errors cover cap breaches (html_too_large, css_too_large, js_too_large, total_too...
Risk signalsAccepts raw HTML/template content (html) · Accepts freeform code/query input (js)
Part of the Dock server.
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AI agents call validate_html to retrieve information from Dock without modifying any data. This is common in research, monitoring, and reporting workflows where the agent needs context before taking action. Because read operations don't change state, they are generally safe to allow without restrictions -- but you may still want rate limits to control API costs.
Even though validate_html only reads data, uncontrolled read access can leak sensitive information or rack up API costs. An agent caught in a retry loop could make thousands of calls per minute. A rate limit gives you a safety net without blocking legitimate use.
Read-only tools are safe to allow by default. No rate limit needed unless you want to control costs.
{
"version": "1",
"default": "deny",
"tools": {
"validate_html": {}
}
}See the full Dock policy for all 64 tools.
These attack patterns abuse exactly the kind of access validate_html gives an agent. Each links to the full case and the policy that stops it:
Other read tools across the catalogue. The same approach applies to each: allow, with a rate cap to control cost.
Pre-flight check on html / css / js BEFORE writing via update_html. Returns { ok, errors, warnings, parsed } where parsed has byte counts per field and dropped (true if the sanitizer would strip anything from html). Errors cover cap breaches (html_too_large, css_too_large, js_too_large, total_too_large) and sanitizer rejection (html_sanitize_rejected, html_sanitize_empty). At v2 the sanitizer accepts <script> and <link> — those used to be smells but are now first-class agent markup; isolation lives in the opaque render iframe, not the sanitizer. The smells still stripped: inline on*= attributes, javascript:/data:text/html URIs, <meta http-equiv> tags. NEVER writes anything. Use when iterating on a payload so you don't burn a write on something the surface would reject.. It is categorised as a Read tool in the Dock MCP Server, which means it retrieves data without modifying state.
Register the Dock MCP server in PolicyLayer and add a rule for validate_html: 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 Dock. Nothing to install.
validate_html 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 validate_html 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 validate_html. 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.
validate_html is provided by the Dock MCP server (https://trydock.ai/api/mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 64 Dock tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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