AI agents call list-charts to retrieve information from PI API MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns chart data without modifying, executing operations on, or deleting any resources. The filtering capability is for refining the returned dataset, not for making changes. It falls squarely into the Read category with low severity since listing charts poses minimal security risk if accessed by an AI agent.
From the tool's definition Tool name 'list-charts' and description 'List all charts with filtering support' indicate a retrieval operation with no side effects.
Documented attack patterns abuse exactly the kind of access list-charts gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and PI API MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for list-charts:
{
"version": "1",
"default": "deny",
"tools": {
"list-charts": {}
}
}list-charts is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all charts with filtering support. It is categorised as a Read tool in the PI API MCP Server MCP Server, which means it retrieves data without modifying state.
Register the PI API MCP Server MCP server in PolicyLayer and add a rule for list-charts: 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 PI API MCP Server. Nothing to install.
list-charts is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the list-charts 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 list-charts. 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.
list-charts is provided by the PI API MCP Server MCP server (mingzilla/pi-api-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from PI API 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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18 PI API MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.