AI agents call explain_code to retrieve information from Claude Code without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool performs static analysis and returns explanatory information about code structure and logic. It has no side effects, does not execute code, and does not modify any data. It is analogous to a code documentation or analysis query, which is purely informational in nature.
From the tool's definition Tool name 'explain_code' and description 'Provides detailed explanation of the given code' indicate a read-only operation that retrieves and presents information about code without modifying, executing, or deleting anything.
Documented attack patterns abuse exactly the kind of access explain_code gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Claude Code, and nothing reaches the server without passing your rules. This is the rule we recommend for explain_code:
{
"version": "1",
"default": "deny",
"tools": {
"explain_code": {}
}
}explain_code is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Provides detailed explanation of the given code. It is categorised as a Read tool in the Claude Code MCP Server, which means it retrieves data without modifying state.
Register the Claude Code MCP server in PolicyLayer and add a rule for explain_code: 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 Claude Code. Nothing to install.
explain_code 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 explain_code 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 explain_code. 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.
explain_code is provided by the Claude Code MCP server (kunihiros/claude-code-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Claude Code, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
7 Claude Code tools catalogued and risk-classified — across an index of 43,000+ MCP servers.