AI agents use player_set_fullscreen to create or update resources in MultiViewer — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MultiViewer environment.
Based on the name, this tool likely sets a player's fullscreen state (on/off), which is a reversible UI modification. No description is provided, which lowers confidence. Grouped with sibling tools like player_set_bounds and player_set_always_on_top that adjust player display properties, this fits a Write category with low severity.
From the tool's definition Tool name: player_set_fullscreen; description is empty and uninformative.
Documented attack patterns abuse exactly the kind of access player_set_fullscreen gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MultiViewer, and nothing reaches the server without passing your rules. This is the rule we recommend for player_set_fullscreen:
{
"version": "1",
"default": "deny",
"tools": {
"player_set_fullscreen": {
"limits": [
{
"counter": "player_set_fullscreen_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}player_set_fullscreen 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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player_set_fullscreen. It is categorised as a Write tool in the MultiViewer MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MultiViewer MCP server in PolicyLayer and add a rule for player_set_fullscreen: 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 MultiViewer. Nothing to install.
player_set_fullscreen 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 player_set_fullscreen 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 player_set_fullscreen. 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.
player_set_fullscreen is provided by the MultiViewer MCP server (robspectre/mvf1). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MultiViewer, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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21 MultiViewer tools catalogued and risk-classified — across an index of 43,000+ MCP servers.