Write an HTML surface's body. Pass any of html / css / js; omitted fields stay unchanged. Pass empty string to clear. The surface renders in a sandboxed iframe on a separate origin (render.trydock.ai) with no access to Dock cookies, storage, or parent DOM — you have free rein inside that boundary...
Risk signalsAccepts raw HTML/template content (html) · Accepts freeform code/query input (js)
Part of the Dock server.
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AI agents use update_html to create or modify resources in Dock. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call update_html repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach Dock.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"update_html": {
"limits": [
{
"counter": "update_html_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full Dock policy for all 64 tools.
These attack patterns abuse exactly the kind of access update_html gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Write an HTML surface's body. Pass any of html / css / js; omitted fields stay unchanged. Pass empty string to clear. The surface renders in a sandboxed iframe on a separate origin (render.trydock.ai) with no access to Dock cookies, storage, or parent DOM — you have free rein inside that boundary. Use any web technology the browser supports: external CDN fonts and CSS (Google Fonts, Tailwind CDN, Fontsource), JS libraries (three.js, GSAP, Chart.js, anime.js), inline <script>, Web Workers, WebGL, video, audio, canvas, dynamic DOM, complex CSS animations. Per-field caps: html 256 KB, css 200 KB, js 200 KB, total 600 KB. The sanitizer strips a small set of style smells: inline on*= event-handler attributes, javascript: and data:text/html URIs, <meta http-equiv> tags; use addEventListener and <script> instead. Requires editor role.. It is categorised as a Write tool in the Dock MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Dock MCP server in PolicyLayer and add a rule for update_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.
update_html is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the update_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 update_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.
update_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.
Free to start. No card required.
4,600+ MCP servers and 31,000+ tools scanned and risk-classified.