Check if a TCP port is open/listening on localhost. Use after run_background to confirm a dev server started. Returns true if something is listening.
AI agents call check_port to retrieve information from DevToolkit MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool performs network reconnaissance by checking port status, which is a read-only diagnostic operation. It retrieves information about listening ports without modifying, executing code, deleting data, or creating financial obligations. The severity is low because port scanning on localhost poses minimal risk; it cannot directly compromise systems or access unauthorized data.
From the tool's definition Tool description states it 'Check[s] if a TCP port is open/listening on localhost' and 'Returns true if something is listening.' This is purely a query operation with no side effects—it only probes the state of a port and returns a boolean result.
Attacks that exploit this kind of access
Check if a TCP port is open/listening on localhost. Use after run_background to confirm a dev server started. Returns true if something is listening. It is categorised as a Read tool in the DevToolkit MCP Server MCP Server, which means it retrieves data without modifying state.
Register the DevToolkit MCP Server MCP server in PolicyLayer and add a rule for check_port: 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 DevToolkit MCP Server. Nothing to install.
check_port 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_port 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_port. 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_port is provided by the DevToolkit MCP Server MCP server (tusharrayamajhi/devtoolkit-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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