AI agents call check_files to retrieve information from Sonarlint without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Even though check_files only reads data, uncontrolled read access leaks sensitive information and racks up API costs — an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.
Attacks that exploit this kind of access
Check multiple files for code quality issues in one call — bugs, code smells, security vulnerabilities. Use when reviewing or modifying several files. Supports glob patterns (e.g. It is categorised as a Read tool in the Sonarlint MCP Server, which means it retrieves data without modifying state.
Register the Sonarlint MCP server in PolicyLayer and add a rule for check_files: 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 Sonarlint. Nothing to install.
check_files 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 check_files 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 check_files. 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.
check_files is provided by the Sonarlint MCP server (@nielspeter/sonarlint-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.