Show buffer metadata (lines, source file, range)
AI agents call buffer_list to retrieve information from Clippy without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and displays buffer metadata (line count, source file reference, and range information) with no side effects. It performs only read operations on clipboard buffer state, making it a Read category tool with low severity since metadata alone poses minimal risk.
From the tool's definition Tool description states 'Show buffer metadata (lines, source file, range)' - a pure query operation that retrieves metadata without modification.
Documented attack patterns abuse exactly the kind of access buffer_list gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Clippy, and nothing reaches the server without passing your rules. This is the rule we recommend for buffer_list:
{
"version": "1",
"default": "deny",
"tools": {
"buffer_list": {}
}
}buffer_list is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Show buffer metadata (lines, source file, range). It is categorised as a Read tool in the Clippy MCP Server, which means it retrieves data without modifying state.
Register the Clippy MCP server in PolicyLayer and add a rule for buffer_list: 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 Clippy. Nothing to install.
buffer_list 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 buffer_list 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 buffer_list. 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.
buffer_list is provided by the Clippy MCP server (neilberkman/clippy). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Clippy, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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7 Clippy tools catalogued and risk-classified — across an index of 43,000+ MCP servers.