# usda_nass_compare_crop_years

Compare 2–7 requested crop years across every hosted area, yield, and production metric for one USDA NASS crop/class. Returns each component value with its own unit and source release file, missing-year evidence, provenance, and caveats. Use this for 'compare 2019 and 2025 corn', '2020 vs 2025 soybean acres and yield', or 'compare winter wheat output across these years'. Final national annual summaries only.

Agent View of the PolicyLayer registry record for `usda_nass_compare_crop_years`. HTML page: https://policylayer.com/tools/io-github-blackboxfoundry-livedatalink/usda-nass-compare-crop-years

## Facts

- Tool: `usda_nass_compare_crop_years`
- Server: Livedatalink (`https://livedatalink.ai/mcp`) — https://policylayer.com/tools/io-github-blackboxfoundry-livedatalink.md
- Homepage: https://github.com/blackboxfoundry/livedatalink
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server auth posture: open
- Server CORS policy: *
- Server rate-limited: no
- Parameters: 4 (2 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `crop` | string | yes | Crop name or supported alias: corn, soybeans, cotton, wheat, winter wheat, durum wheat, or spring wheat. |
| `years` | array | yes | Two to seven distinct crop years. |
| `crop_class` | string | no | Optional class. Required for bare 'wheat': winter, durum, or spring (excluding durum). |
| `response_format` | string | no | Human-readable markdown or machine-readable JSON. Default markdown. |

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": "usda_nass_compare_crop_years",
    "arguments": {
      "crop": "<crop>",
      "years": []
    }
  }
}
```

## Why usda_nass_compare_crop_years is rated Low

Even though usda_nass_compare_crop_years only reads data, uncontrolled read access leaks sensitive information and racks up API costs: an agent caught in a retry loop can make thousands of calls a minute without anyone noticing.

Risk signals: Bulk/mass operation — affects multiple targets

## Use case

AI agents call usda_nass_compare_crop_years to retrieve information from Livedatalink 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 Livedatalink:

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

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## 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`

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