# lookup_factor

Look up a single greenhouse-gas emission factor by its canonical key. Returns the value plus an audit envelope: provenance (publisher, exact source cell, retrieval date, LICENCE and whether it may be redistributed, with the attribution the licence requires) and verification (whether the per-gas components sum to the headline, the GWP set, and the source note stating what the publisher did NOT provide). If the key does not exist you get candidate keys back rather than a dead end. Use search_factors first if you do not know the key.

Agent View of the PolicyLayer registry record for `lookup_factor`. HTML page: https://policylayer.com/tools/com-greencalculus-api/lookup-factor

## Facts

- Tool: `lookup_factor`
- Server: Api (`https://mcp.greencalculus.com`) — https://policylayer.com/tools/com-greencalculus-api.md
- Homepage: https://github.com/https://mcp.greencalculus.com
- Risk category: Read (Low risk)
- Registry record: grade D, identity unverified
- Server auth posture: open
- Server CORS policy: *
- Server rate-limited: no
- Parameters: 1 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `key` | string | yes | Canonical factor key, e.g. "grid.deu.electricity.location_based". |

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": "lookup_factor",
    "arguments": {
      "key": "<key>"
    }
  }
}
```

## Why lookup_factor is rated Low

Even though lookup_factor 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.

## Use case

AI agents call lookup_factor to retrieve information from Api 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 Api:

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

## Other tools on Api (10)

- `calculate_activity` — Read — https://policylayer.com/tools/com-greencalculus-api/calculate-activity.md
- `calculate_business_travel` — Read — https://policylayer.com/tools/com-greencalculus-api/calculate-business-travel.md
- `calculate_electricity` — Read — https://policylayer.com/tools/com-greencalculus-api/calculate-electricity.md
- `calculate_embodied` — Read — https://policylayer.com/tools/com-greencalculus-api/calculate-embodied.md
- `calculate_freight` — Read — https://policylayer.com/tools/com-greencalculus-api/calculate-freight.md
- `calculate_pcaf` — Read — https://policylayer.com/tools/com-greencalculus-api/calculate-pcaf.md
- `calculate_spend` — Read — https://policylayer.com/tools/com-greencalculus-api/calculate-spend.md
- `explain_absence` — Read — https://policylayer.com/tools/com-greencalculus-api/explain-absence.md
- `search_factors` — Read — https://policylayer.com/tools/com-greencalculus-api/search-factors.md
- `resolve_factor` — Write — https://policylayer.com/tools/com-greencalculus-api/resolve-factor.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=com-greencalculus-api · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/com-greencalculus-api