nmap-mcp

Overview Schema Source Related Servers Discussions Admin

discover-hosts

Identify live hosts on a network using ping scan without port scanning. Returns lists of responsive and unresponsive hosts for network assessment.

Instructions

Discover live hosts on a network without performing a port scan.

Uses nmap ping scan (-sn) to identify which hosts are up on the target network. This is typically the first step in a network assessment.

IMPORTANT: Only scan networks you are authorized to scan.

Returns: HostDiscoveryResult with lists of hosts that are up and down.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "target": "<target>"
    },
    "name": "discover-hosts"
  }
}

Input Schema

Name	Required	Description	Default
`target`	Yes	Network range to scan: CIDR notation (192.168.1.0/24) or IP range. Max /24 network size.
`timing`	No	Timing template: "paranoid" through "insane". Default: "normal".	normal
`timeout`	No	Maximum scan duration in seconds. Default: 600.

Output Schema

Name	Required	Description
`hosts_up`	No	List of hosts that are up
`hosts_down`	No	List of hosts that are down
`total_scanned`	No	Total hosts scanned
`scan_stats`	No	Scan statistics

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0May 28, 2026

TDQS

A4.3/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the burden of disclosing behavior. It clearly states the tool uses nmap ping scan (-sn), explicitly rules out port scanning, and describes the return type (HostDiscoveryResult with up/down host lists). It also adds a safety note about authorized scanning. It stops short of detailing edge cases (e.g., hosts that block ICMP), but the core behavioral disclosure is solid.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded with the core purpose. Every sentence earns its place: purpose, method, usage context, authorization warning, and return summary. No wasted words or filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given that the output schema exists (covering the return value) and the input schema is fully documented, the description provides all necessary operational context: what it does, how it does it (nmap -sn), when to use it (first step), and a safety constraint. It is complete for a straightforward host-discovery tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema already provides 100% coverage of all three parameters (target, timing, timeout) with descriptions. The tool description itself adds no additional parameter semantics beyond what the schema offers, so a baseline score of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: discovering live hosts without a port scan. It uses a specific verb ('Discover'), identifies the resource (live hosts on a network), and distinguishes itself from siblings by explicitly noting it performs no port scan and is the typical first step in a network assessment.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear usage context, noting this is typically the first step in a network assessment and that it does not perform a port scan. It also includes an authorization warning. However, it does not explicitly name alternative sibling tools (e.g., scan-ports) for follow-up steps, so it falls just short of full explicit guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server