AI agents use favorite-prompt to create or update resources in MCP Prompt Manager — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Prompt Manager environment.
This tool modifies metadata (favorite status) of an existing prompt. It's a reversible write operation — favorites can be added or removed. No data is deleted, no code is executed, and there are no financial implications. Blast radius is minimal since it only toggles a favorite flag.
From the tool's definition Add or remove a prompt from favorites
Documented attack patterns abuse exactly the kind of access favorite-prompt gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Prompt Manager, and nothing reaches the server without passing your rules. This is the rule we recommend for favorite-prompt:
{
"version": "1",
"default": "deny",
"tools": {
"favorite-prompt": {
"limits": [
{
"counter": "favorite-prompt_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}favorite-prompt 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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Add or remove a prompt from favorites. It is categorised as a Write tool in the MCP Prompt Manager MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MCP Prompt Manager MCP server in PolicyLayer and add a rule for favorite-prompt: 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 MCP Prompt Manager. Nothing to install.
favorite-prompt 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 favorite-prompt 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 favorite-prompt. 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.
favorite-prompt is provided by the MCP Prompt Manager MCP server (tae4an/mcp-prompt-manager). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Prompt Manager, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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33 MCP Prompt Manager tools catalogued and risk-classified — across an index of 43,000+ MCP servers.