AI agents use post_comment to create or update resources in Figma MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Figma MCP Server environment.
Posting a comment creates new data (a comment object) in a Figma file, which is reversible (comments can be deleted). This is a Write operation with medium severity because misuse could spam or clutter design files with many unwanted comments, but the impact is limited to annotation data that doesn't destructively alter the actual design or have financial consequences.
From the tool's definition Tool name 'post_comment' and description 'Post a comment on a node in a Figma file' indicate creation of new comment data on a design file.
Documented attack patterns abuse exactly the kind of access post_comment gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Figma MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for post_comment:
{
"version": "1",
"default": "deny",
"tools": {
"post_comment": {
"limits": [
{
"counter": "post_comment_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}post_comment stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Post a comment on a node in a Figma file. It is categorised as a Write tool in the Figma MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Figma MCP Server MCP server in PolicyLayer and add a rule for post_comment: 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 Figma MCP Server. Nothing to install.
post_comment 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 post_comment 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 post_comment. 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.
post_comment is provided by the Figma MCP Server MCP server (matthewdailey/figma-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Figma MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
5 Figma MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.