> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sector8.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# POST /evaluate

> Evaluate a tool call against the active policy. Returns an admission decision.

## Request

```http theme={null}
POST /evaluate HTTP/1.1
Host: api.sector8.ai
Authorization: Bearer YOUR_API_KEY
X-Client-ID: YOUR_CLIENT_ID
Content-Type: application/json
```

```json theme={null}
{
  "tool_name": "bash",
  "arguments": {
    "command": "cat /etc/passwd"
  },
  "session_id": "session-abc123",
  "user_id": "engineer-42",
  "context": {
    "source": "claude_code",
    "project": "backend"
  }
}
```

## Request fields

| Field        | Required | Description                                                                                   |
| ------------ | -------- | --------------------------------------------------------------------------------------------- |
| `tool_name`  | ✓        | Tool being called: `bash`, `read_file`, `write_file`, `web_fetch`, or custom registered tools |
| `arguments`  | ✓        | Tool arguments as a JSON object                                                               |
| `session_id` | ✓        | Stable session identifier — required for multi-turn escalation scoring                        |
| `user_id`    |          | Engineer or agent identifier for per-user telemetry                                           |
| `context`    |          | Additional metadata included in the telemetry record                                          |

## Response — ALLOW

```json theme={null}
{
  "decision": "ALLOW",
  "reason_code": null,
  "pre_filter_decision": "PASS",
  "semantic_score": 0.08,
  "semantic_cluster": null,
  "policy_version_id": "0dbca364d66447469637bafa2282e635124fcb99eecd6383038e3b652577ebc7",
  "decision_trace_id": "17e797c0-eb5c-4f97-b4a1-2d3e4f5a6b7c",
  "evidence_hash": null,
  "has_forensic_payload": false
}
```

## Response — DENY

```json theme={null}
{
  "decision": "DENY",
  "reason_code": "SENSITIVE_PATH_BLOCKED",
  "pre_filter_decision": "BLOCK",
  "semantic_score": 0.94,
  "semantic_cluster": "pii_exfiltration",
  "policy_version_id": "0dbca364d66447469637bafa2282e635124fcb99eecd6383038e3b652577ebc7",
  "decision_trace_id": "32819155-d21a-49c8-9509-79338d980fa9",
  "evidence_hash": "bdbde1558fb883573b0f6e8630ccba1edaf6bed8cb035fa6a48912809149f287",
  "has_forensic_payload": true
}
```

## Response fields

| Field                  | Type         | Description                                                                               |
| ---------------------- | ------------ | ----------------------------------------------------------------------------------------- |
| `decision`             | string       | `"ALLOW"` or `"DENY"`                                                                     |
| `reason_code`          | string\|null | Machine-readable denial reason. See [reason codes](/api-reference/overview#reason-codes). |
| `pre_filter_decision`  | string       | `"BLOCK"`, `"PASS"`, or `"REVIEW"`                                                        |
| `semantic_score`       | number       | 0.0–1.0 semantic threat similarity score                                                  |
| `semantic_cluster`     | string\|null | Nearest threat cluster when score is significant                                          |
| `policy_version_id`    | string       | Signed policy bundle hash — links decision to policy state                                |
| `decision_trace_id`    | string       | UUID — links to full admission trace in telemetry                                         |
| `evidence_hash`        | string\|null | SHA-256 of blocked payload. Present on all DENY records.                                  |
| `has_forensic_payload` | boolean      | `true` on 100% of DENY records                                                            |

<Note>
  `evidence_hash` is a cryptographic hash of the blocked payload. It can be used to verify the contents of a denial record have not been tampered with after the fact.
</Note>