AI agents use set_layer_opacity to create or update resources in Piskel MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Piskel MCP Server environment.
This tool alters the state of a pixel art project by adjusting layer transparency. The change is reversible (opacity can be reset to a different value), placing it in the Write category rather than Destructive. Severity is medium because misuse could render artwork unintentionally transparent or invisible, degrading a project's quality, but no data is permanently lost.
From the tool's definition Tool modifies layer opacity parameter (0.0 to 1.0), which changes the visual rendering of existing layers reversibly. This is a property modification operation.
Documented attack patterns abuse exactly the kind of access set_layer_opacity gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Piskel MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for set_layer_opacity:
{
"version": "1",
"default": "deny",
"tools": {
"set_layer_opacity": {
"limits": [
{
"counter": "set_layer_opacity_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_layer_opacity 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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Set the opacity of a layer (0.0 to 1.0). It is categorised as a Write tool in the Piskel MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Piskel MCP Server MCP server in PolicyLayer and add a rule for set_layer_opacity: 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 Piskel MCP Server. Nothing to install.
set_layer_opacity 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 set_layer_opacity 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 set_layer_opacity. 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.
set_layer_opacity is provided by the Piskel MCP Server MCP server (yafeiaa/piskel-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Piskel 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.
45 Piskel MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.