# explain_absence

Ask why a factor is NOT in the corpus. The reasoned counterpart to coverage: where a country reports zero rows for an inventory family, this says whether that is the world's limit or our backlog. Five classifications: "structural" (no publisher issues this anywhere — stop looking, and do not silently substitute another country), "not_yet_sourced" (a publisher exists and is named; it is our backlog), "refused" (we found it and declined — the reason is stated), "held_not_counted" (we DO hold it — see we_hold for the key), "coupled" (empty only because another family is empty). Each record names the publisher checked, the route tried, a confidence and a review date, and reports stale:true once past review. These are authored judgements about what the world publishes, not values derived from our data. Call this before concluding that a gap is permanent, and before telling a user to look elsewhere.

Agent View of the PolicyLayer registry record for `explain_absence`. HTML page: https://policylayer.com/tools/com-greencalculus-api/explain-absence

## Facts

- Tool: `explain_absence`
- 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: 3
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `family` | string | no | Inventory family, e.g. "water", "wtt", "travel", "spend", "heat". |
| `country` | string | no | ISO-3166 alpha-3 code, e.g. "can". |
| `classification` | string | no | Filter: structural \| not_yet_sourced \| refused \| held_not_counted \| coupled. |

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": "explain_absence",
    "arguments": {}
  }
}
```

## Why explain_absence is rated Low

Even though explain_absence 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 explain_absence 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": {
    "explain_absence": {}
  }
}
```

## 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
- `lookup_factor` — Read — https://policylayer.com/tools/com-greencalculus-api/lookup-factor.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