AI agents call get_uncovered_lines 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 queries and returns coverage data (uncovered lines) from SimpleCov reports. It performs no modifications, deletions, or external operations. It is read-only analysis functionality designed to help developers understand test coverage gaps.
From the tool's definition The tool retrieves a list of uncovered line numbers from a specific file. The Japanese description translates to 'Get a list of uncovered line numbers for a specific file.
Attacks that exploit this kind of access
特定ファイルの未カバー行番号のリストを取得する。テスト追加の参考に。. 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 get_uncovered_lines: 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.
get_uncovered_lines 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 get_uncovered_lines 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 get_uncovered_lines. 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.
get_uncovered_lines 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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