Adjust brightness and contrast of a layer. Parameters: - brightness: -127 to +127 (default 0) - contrast: -127 to +127 (default 0) - image_index: Target image index (default 0) - layer_name: Layer to adjust; defaults to active layer Returns status dict.
AI agents use adjust_brightness_contrast to create or update resources in Gimp — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Gimp environment.
This tool creates reversible modifications to image data. Brightness and contrast adjustments are non-destructive edits that can be undone or overwritten. The operation does not delete data (not Destructive), execute arbitrary code beyond GIMP's API (not Execute), involve financial transactions (not Financial), or merely query information (not Read). It fits the Write category as a reversible data modification.
From the tool's definition Tool modifies image layer properties (brightness and contrast values) through parameters that adjust visual appearance.
Documented attack patterns abuse exactly the kind of access adjust_brightness_contrast gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Gimp, and nothing reaches the server without passing your rules. This is the rule we recommend for adjust_brightness_contrast:
{
"version": "1",
"default": "deny",
"tools": {
"adjust_brightness_contrast": {
"limits": [
{
"counter": "adjust_brightness_contrast_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}adjust_brightness_contrast 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.
Free to start. No card required.
Adjust brightness and contrast of a layer. Parameters: - brightness: -127 to +127 (default 0) - contrast: -127 to +127 (default 0) - image_index: Target image index (default 0) - layer_name: Layer to adjust; defaults to active layer Returns status dict. It is categorised as a Write tool in the Gimp MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Gimp MCP server in PolicyLayer and add a rule for adjust_brightness_contrast: 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 Gimp. Nothing to install.
adjust_brightness_contrast 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 adjust_brightness_contrast 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 adjust_brightness_contrast. 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.
adjust_brightness_contrast is provided by the Gimp MCP server (maorcc/gimp-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Gimp, 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.
79 Gimp tools catalogued and risk-classified — across an index of 43,000+ MCP servers.