AI agents use set_price to create or update resources in Lemonade Stand MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Lemonade Stand MCP Server environment.
The tool updates a game parameter (price) but does not delete data, execute arbitrary code, move money, or trigger external operations. The change is reversible—the price can be set again to a different value.
From the tool's definition Tool is named 'set_price' and described as 'Set the price per cup of lemonade', which modifies game state (pricing strategy) in a reversible manner. This is consistent with Write-category tools that create or modify data without destructive effects.
Documented attack patterns abuse exactly the kind of access set_price gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Lemonade Stand MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for set_price:
{
"version": "1",
"default": "deny",
"tools": {
"set_price": {
"limits": [
{
"counter": "set_price_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_price 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 price per cup of lemonade. It is categorised as a Write tool in the Lemonade Stand MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Lemonade Stand MCP Server MCP server in PolicyLayer and add a rule for set_price: 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 Lemonade Stand MCP Server. Nothing to install.
set_price 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_price 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_price. 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_price is provided by the Lemonade Stand MCP Server MCP server (jimmcq/lemonade-stand-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Lemonade Stand MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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5 Lemonade Stand MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.