Check if a specific port is open on a host by providing an IP address or hostname and a port number. Get an immediate yes/no answer to verify network connectivity and service availability.
Check if a specific port is open on a host
| Name | Required | Description | Default |
|---|---|---|---|
| host | Yes | IP address or hostname | |
| port | Yes | Port number to check |
Changes observed during successful MCP inspections.
v1.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden; saying 'check if ... is open' communicates a read-only network probe and implies no destructive side effects. It does not disclose protocol (TCP/UDP), timeout behavior, or return format, which keeps it from being fully transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
One short front-loaded sentence with no filler or repeated title content. Every word contributes meaning.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple two-parameter tool the description is adequate, but with no output schema or annotations it omits the return contract (true/false) and edge cases like closed or filtered ports. An agent can call it correctly but not know exactly what to expect back.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the parameters are already fully documented. The description only rephrases host and port without adding semantics beyond the schema, so the baseline 3 applies.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb ('check') and resource ('port on a host') and includes the qualifier 'specific,' which distinguishes it from sibling tools like scan_ports and scan_network that imply broader scanning. The purpose is immediately unambiguous.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The qualifier 'specific' implies this is the right tool for a single port check rather than a scan, so usage context is loosely conveyed. However, it does not explicitly mention alternatives or state when not to use it, leaving the agent to infer routing from sibling names.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.