# lookup_failure

Search Denpex's bundled failure encyclopedia by error code, keyword, or symptom (e.g. 'Xid 79', 'NCCL timeout', 'loss is NaN', 'CUDA out of memory'). Returns the most relevant known failures with their fixes. Works fully offline and costs no quota — but the BUNDLE is a subset: 312 classes on-host against the full corpus the cloud ranks. Use diagnose_crash instead when you have a full crash log.

Agent View of the PolicyLayer registry record for `lookup_failure`. HTML page: https://policylayer.com/tools/denpex-mcp/lookup-failure

## Facts

- Tool: `lookup_failure`
- Server: Denpex (`denpex-mcp`) — https://policylayer.com/tools/denpex-mcp.md
- Install: `npx -y denpex-mcp`
- Homepage: https://www.npmjs.com/package/denpex-mcp
- Risk category: Read (Low risk)
- Registry record: grade F, identity unverified
- Server rate-limited: no
- Parameters: 2 (1 required)
- Recommended policy verdict: Allowed

## Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `limit` | integer | no | Max results (default 5). |
| `query` | string | yes | Error code, message, or symptom to look up. |

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_failure",
    "arguments": {
      "query": "<query>"
    }
  }
}
```

## Why lookup_failure is rated Low

Even though lookup_failure 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_failure to retrieve information from Denpex 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 Denpex:

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

## Other tools on Denpex (14)

- `compare_runs` — Execute — https://policylayer.com/tools/denpex-mcp/compare-runs.md
- `diff_environments` — Execute — https://policylayer.com/tools/denpex-mcp/diff-environments.md
- `node_health` — Execute — https://policylayer.com/tools/denpex-mcp/node-health.md
- `predict_failures` — Execute — https://policylayer.com/tools/denpex-mcp/predict-failures.md
- `analyze_cascade` — Read — https://policylayer.com/tools/denpex-mcp/analyze-cascade.md
- `ask_followup` — Read — https://policylayer.com/tools/denpex-mcp/ask-followup.md
- `check_quota` — Read — https://policylayer.com/tools/denpex-mcp/check-quota.md
- `check_versions` — Read — https://policylayer.com/tools/denpex-mcp/check-versions.md
- `diagnose_crash` — Read — https://policylayer.com/tools/denpex-mcp/diagnose-crash.md
- `list_incidents` — Read — https://policylayer.com/tools/denpex-mcp/list-incidents.md
- `preflight_check` — Read — https://policylayer.com/tools/denpex-mcp/preflight-check.md
- `recent_diagnoses` — Read — https://policylayer.com/tools/denpex-mcp/recent-diagnoses.md
- `validate_checkpoint` — Read — https://policylayer.com/tools/denpex-mcp/validate-checkpoint.md
- `submit_fix_outcome` — Write — https://policylayer.com/tools/denpex-mcp/submit-fix-outcome.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=denpex-mcp · API: https://policylayer.com/registry/api · Policy library: https://policylayer.com/policies/denpex-mcp