Find what calls a function or what a function calls by using the function name. Perfect for understanding code flow and dependencies - faster than manually tracing through files
AI agents call callHierarchy to retrieve information from MCP Server for VS Code without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
callHierarchy retrieves and analyzes static code relationship data without modifying, executing, or deleting anything. It is a read-only introspection tool for code navigation. The low severity reflects minimal blast radius if misused by an agent — worst case is understanding unwanted code relationships, which has no destructive or operational consequences.
From the tool's definition Tool description explicitly states it 'Find[s] what calls a function or what a function calls' and 'understand[s] code flow and dependencies' — purely informational queries with no side effects.
Documented attack patterns abuse exactly the kind of access callHierarchy gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Server for VS Code, and nothing reaches the server without passing your rules. This is the rule we recommend for callHierarchy:
{
"version": "1",
"default": "deny",
"tools": {
"callHierarchy": {}
}
}callHierarchy is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
Free to start. No card required.
Find what calls a function or what a function calls by using the function name. Perfect for understanding code flow and dependencies - faster than manually tracing through files. It is categorised as a Read tool in the MCP Server for VS Code MCP Server, which means it retrieves data without modifying state.
Register the MCP Server for VS Code MCP server in PolicyLayer and add a rule for callHierarchy: 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 MCP Server for VS Code. Nothing to install.
callHierarchy 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 callHierarchy 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 callHierarchy. 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.
callHierarchy is provided by the MCP Server for VS Code MCP server (malvex/mcp-server-vscode). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Server for VS 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.
25 MCP Server for VS Code tools catalogued and risk-classified — across an index of 43,000+ MCP servers.