The Api.Ping method outputs a unique ID for the CPU used. You can use it to determine whether the CPU can be reached. The CPU ID comprises a 28-byte string. The system assigns a new, unique CPU ID after each restart (POWER ON - POWER OFF) or warm start of the CPU. By comparing this with previousl...
AI agents call Api-Ping to retrieve information from ThinkPLC-MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a pure read/probe operation that retrieves a CPU identifier and connectivity status. It has no side effects, requires no authentication, and cannot modify any state. Misuse by an AI agent would at most reveal infrastructure reachability information, making severity low.
From the tool's definition 'outputs a unique ID for the CPU used', 'determine whether the CPU can be reached', 'No authorization is required for calling the Api.Ping method'
Documented attack patterns abuse exactly the kind of access Api-Ping gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and ThinkPLC-MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for Api-Ping:
{
"version": "1",
"default": "deny",
"tools": {
"Api-Ping": {}
}
}Api-Ping is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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The Api.Ping method outputs a unique ID for the CPU used. You can use it to determine whether the CPU can be reached. The CPU ID comprises a 28-byte string. The system assigns a new, unique CPU ID after each restart (POWER ON - POWER OFF) or warm start of the CPU. By comparing this with previously output IDs, you can also determine whether the CPU was restarted in the meantime. No authorization is required for calling the Api.Ping method. It is categorised as a Read tool in the ThinkPLC-MCP MCP Server, which means it retrieves data without modifying state.
Register the ThinkPLC- MCP server in PolicyLayer and add a rule for Api-Ping: 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 ThinkPLC-MCP. Nothing to install.
Api-Ping 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 Api-Ping 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 Api-Ping. 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.
Api-Ping is provided by the ThinkPLC- MCP server (mrwan84/thinkplc-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from ThinkPLC-MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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23 ThinkPLC-MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.