AI agents use apply_master_spread to create or update resources in InDesign UXP MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your InDesign UXP MCP Server environment.
Applying a master spread modifies page formatting, layout, and linked styles across one or more pages in an InDesign document. This is a Write operation because it alters document state reversibly—the change can be undone or a different master spread applied. It is not Destructive because no data is deleted, and it is not Execute because the tool does not run arbitrary code.
From the tool's definition Tool name 'apply_master_spread' and description 'Apply a master spread to pages' indicates modification of page layout and styling properties. This is a reversible change to document structure and appearance.
Documented attack patterns abuse exactly the kind of access apply_master_spread gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and InDesign UXP MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for apply_master_spread:
{
"version": "1",
"default": "deny",
"tools": {
"apply_master_spread": {
"limits": [
{
"counter": "apply_master_spread_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}apply_master_spread 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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Apply a master spread to pages. It is categorised as a Write tool in the InDesign UXP MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the InDesign UXP MCP Server MCP server in PolicyLayer and add a rule for apply_master_spread: 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 InDesign UXP MCP Server. Nothing to install.
apply_master_spread 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 apply_master_spread 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 apply_master_spread. 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.
apply_master_spread is provided by the InDesign UXP MCP Server MCP server (theloniuser/indesign-uxp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 135 InDesign UXP MCP Server tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
135 InDesign UXP MCP Server tools catalogued and risk-classified — across an index of 42,500+ MCP servers.