Evaluate Policy

Evaluate a deployed policy by module and function name. The policy must already be deployed to the engine before it can be called through this endpoint.

Endpoint

POST /api/v1/policies/evaluate

Required Role

MEMBER

Headers

Header	Value	Required
Authorization	Bearer <token>	Yes
Content-Type	application/json	Yes
X-Tenant-ID	Tenant identifier string	Yes

Request Body

{
  "policyModule": "string",
  "policyFunction": "string",
  "context": [{}]
}

Field	Type	Required	Description
policyModule	string	Yes	The fully-qualified module name as declared in the CNL source (e.g. "Loan.Approval").
policyFunction	string	Yes	The function name within the module to invoke (e.g. "isEligible").
context	array<object>	Yes	An ordered list of argument objects passed positionally to the policy function. The structure of each object must match the parameter schema declared in the policy. Pass an empty array [] for zero-argument functions.

Response Body

{
  "result": "<any>",
  "executionTimeMs": 0,
  "error": null,
  "decisionTrace": null
}

Field	Type	Description
result	any	The value returned by the policy function. The type matches the declared return type of the function (boolean, number, string, or object).
executionTimeMs	number	Wall-clock time in milliseconds from request receipt to response dispatch.
error	string | null	Human-readable error message if evaluation failed; null on success.
decisionTrace	object | null	Structured trace of rule evaluation steps. Always null for this endpoint. Use /evaluate-source?trace=true to obtain a trace.

HTTP Status Codes

Status	Meaning
200 OK	Evaluation completed. Check error field — a non-null value indicates a policy-level failure while the HTTP call itself succeeded.
400 Bad Request	Malformed request body or missing required fields.
401 Unauthorized	Missing or invalid bearer token.
403 Forbidden	Token is valid but the caller lacks the MEMBER role.
404 Not Found	No deployed policy found matching policyModule + policyFunction.
500 Internal Server Error	Unexpected engine failure.

Examples

curl

curl -X POST https://policy.aster-lang.dev/api/v1/policies/evaluate \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -H "X-Tenant-ID: acme-corp" \
  -d '{
    "policyModule": "Loan.Approval",
    "policyFunction": "isEligible",
    "context": [
      {
        "applicantAge": 30,
        "annualIncome": 75000,
        "creditScore": 720,
        "requestedAmount": 25000
      }
    ]
  }'

JavaScript

const response = await fetch(
  'https://policy.aster-lang.dev/api/v1/policies/evaluate',
  {
    method: 'POST',
    headers: {
      Authorization: 'Bearer <token>',
      'Content-Type': 'application/json',
      'X-Tenant-ID': 'acme-corp',
    },
    body: JSON.stringify({
      policyModule: 'Loan.Approval',
      policyFunction: 'isEligible',
      context: [
        {
          applicantAge: 30,
          annualIncome: 75000,
          creditScore: 720,
          requestedAmount: 25000,
        },
      ],
    }),
  }
);

const data = await response.json();
// data.result  → true | false | number | string | object
// data.error   → null on success

Example Response

{
  "result": true,
  "executionTimeMs": 4,
  "error": null,
  "decisionTrace": null
}