# subnet_mask_info

Get subnet mask from prefix length.

Agent View of the PolicyLayer registry record for `subnet_mask_info`. HTML page: https://policylayer.com/tools/io-tinyfn-tinyfn/subnet-mask-info

## Facts

- Tool: `subnet_mask_info`
- Server: TinyFn (`https://api.tinyfn.io/mcp/all/`) — https://policylayer.com/tools/io-tinyfn-tinyfn.md
- Homepage: https://github.com/tinyfn-io/tinyfn-mcp
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server rate-limited: no
- Parameters: 1 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `prefix_length` | integer | yes | CIDR prefix length (0-32) |

Parameters from the server's own tool schema.

## Example call (MCP tools/call, JSON-RPC 2.0)

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "subnet_mask_info",
    "arguments": {
      "prefix_length": 0
    }
  }
}
```

## Why subnet_mask_info is rated Low

This tool performs a deterministic mathematical conversion from a CIDR prefix length to a subnet mask notation—a pure read operation with no side effects. It retrieves computed data without altering any system state or triggering external operations. Blast radius from misuse is negligible, as incorrect subnet mask lookups cannot compromise security or functionality beyond providing wrong information to the agent.

From the tool's own definition: "Tool name 'subnet_mask_info' and description 'Get subnet mask from prefix length' indicate a query/lookup operation that retrieves network configuration information without modifying any state or executing external operations."

## Use case

AI agents call subnet_mask_info to retrieve information from TinyFn without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.

## Recommended policy (PolicyLayer)

Verdict: **Allowed**. Enforced by the PolicyLayer MCP gateway (https://policylayer.com/mcp-gateway) before a call reaches TinyFn:

```json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "subnet_mask_info": {}
  }
}
```

## Other tools on TinyFn (571)

- `array_compact` — Destructive — https://policylayer.com/tools/io-tinyfn-tinyfn/array-compact.md
- `array_dedupe` — Destructive — https://policylayer.com/tools/io-tinyfn-tinyfn/array-dedupe.md
- `truncate_2` — Destructive — https://policylayer.com/tools/io-tinyfn-tinyfn/truncate-2.md
- `generate_hmac` — Execute — https://policylayer.com/tools/io-tinyfn-tinyfn/generate-hmac.md
- `random_float_2` — Execute — https://policylayer.com/tools/io-tinyfn-tinyfn/random-float-2.md
- `random_string_2` — Execute — https://policylayer.com/tools/io-tinyfn-tinyfn/random-string-2.md
- `random_weighted_choice` — Execute — https://policylayer.com/tools/io-tinyfn-tinyfn/random-weighted-choice.md
- `roll_dice` — Execute — https://policylayer.com/tools/io-tinyfn-tinyfn/roll-dice.md
- `null` — Other — https://policylayer.com/tools/io-tinyfn-tinyfn/null.md
- `absolute_value` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/absolute-value.md
- `acres_to_hectares` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/acres-to-hectares.md
- `add` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/add.md
- `adler32_checksum` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/adler32-checksum.md
- `analogous_colors` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/analogous-colors.md
- `analyze_password` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/analyze-password.md
- `array_difference` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-difference.md
- `array_first` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-first.md
- `array_frequency` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-frequency.md
- `array_interleave` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-interleave.md
- `array_intersection` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-intersection.md
- `array_last` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-last.md
- `array_nth` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-nth.md
- `array_partition` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-partition.md
- `array_repeat` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-repeat.md
- `array_reverse` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-reverse.md
- `array_rotate` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-rotate.md
- `array_slice` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-slice.md
- `array_symmetric_difference` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-symmetric-difference.md
- `array_union` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-union.md
- `array_unzip` — Read — https://policylayer.com/tools/io-tinyfn-tinyfn/array-unzip.md
- …and 541 more: https://policylayer.com/tools/io-tinyfn-tinyfn.md

## For agents

This record is a snapshot. Live verdicts and the full registry:

- Check every server in your MCP config at once: `npx -y policylayer stack`
- Vet a server before you add it: install the mcp-precheck skill — `npx skills add https://policylayer.com` (skill text: https://policylayer.com/skill.md)
- Query the registry over MCP: endpoint `https://api.policylayer.com/mcp` — tools `check_mcp_server`, `check_mcp_stack`, `check_tool`, `search_registry`, `get_change_events`

---

Source: the PolicyLayer MCP registry — one continuously verified record per MCP server. Full record: https://policylayer.com/registry?q=io-tinyfn-tinyfn · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/io-tinyfn-tinyfn