fios-mcp

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set_lan_settings

Destructive

Change the router's LAN IP, subnet mask, and DHCP pool with a preview of stranded reservations, forwards, routes, and DMZ entries, then confirm the two-phase update.

Instructions

Change the router's LAN address, mask and DHCP pool (needs features.allow_lan_change).

The preview lists reservations, forwards, routes and DMZ entries the new subnet would strand. If the address changes the router moves and this session ends: the result gives the new URL; the MCP server must be restarted with FIOS_ROUTER_URL pointing there. Two-phase.

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": {
      "ip": "<ip>"
    },
    "name": "set_lan_settings"
  }
}

Input Schema

Name	Required	Default
`ip`	Yes
`mask`	No	255.255.255.0
`confirm`	No
`dhcp_end`	No
`dhcp_start`	No
`dhcp_enabled`	No
`expected_etag`	No
`lease_time_min`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 5, 2026

TDQS

A4.3/5.0

Behavior5/5

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

Annotations already flag destructiveHint=true, but the description adds consequences the annotations cannot convey: the preview enumerates stranded reservations, forwards, routes and DMZ entries, and an address change relocates the router, ends the session, and requires restarting the MCP server with FIOS_ROUTER_URL pointed at the returned URL. This is exactly the operational context an agent needs before a self-severing mutation.

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

Conciseness4/5

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

Four short lines, front-loaded with the action and the feature gate, followed by the risk preview and then the session-ending consequence. The terse "Two-phase." fragment is slightly cryptic but earns its brevity given the surrounding context.

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

Completeness4/5

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

For a destructive, session-terminating mutation with an output schema present, the description covers the preconditions, the dry-run disclosure, and the aftermath; the output schema handles return values. The remaining hole is the undocumented etag/lease/DHCP-enable parameters, which an agent must infer from the schema alone.

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?

Schema description coverage is 0% across 8 parameters, and the description only accounts for address, mask and the DHCP pool. It says nothing about expected_etag (apparently optimistic concurrency), lease_time_min, or dhcp_enabled, though "Two-phase" does hint at the role of confirm. Partial compensation for a real coverage gap.

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?

"Change the router's LAN address, mask and DHCP pool" is a precise verb plus resource plus the exact fields affected, and the naming parallel with the sibling get_lan_settings makes the read/write split obvious without opening either schema.

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?

It states the precondition (features.allow_lan_change) and calls out the two-phase workflow, so an agent knows a preview happens before commitment. It does not explicitly say to read current values with get_lan_settings first or when to abort, so it stops short of full when/when-not guidance.

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