AI agents call list_files to retrieve information from Simplecov without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and queries coverage data from SimpleCov reports with no side effects. It performs listing, filtering, and sorting operations—all Read category operations.
From the tool's definition list_files returns a list of coverage target files and coverage rates with sorting and filtering capabilities. The description indicates it 'returns' (カバレッジ対象ファイルの一覧とカバレッジ率を返す) data without modification.
Attacks that exploit this kind of access
カバレッジ対象ファイルの一覧とカバレッジ率を返す。ソートやフィルタが可能。. It is categorised as a Read tool in the Simplecov MCP Server, which means it retrieves data without modifying state.
Register the Simplecov MCP server in PolicyLayer and add a rule for list_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 Simplecov. Nothing to install.
list_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 list_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 list_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.
list_files is provided by the Simplecov MCP server (ryo-ymd/simplecov-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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