# BeliefState Evaluate Belief Scenario

> BeliefState Evaluate Belief Scenario is a paid API for AI agents from beliefstate.ai, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Evaluates a structured analyst belief (investment thesis) against a set of user-supplied scenario assumptions to determine updated outcomes or validity given current condition statuses.

## Facts

- Endpoint: POST https://beliefstate.ai/v1/research/evaluate_belief_scenario?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/beliefstate-evaluate-belief-scenario-d21df308
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HA_gUZUEfAZx1FJkTDPGj

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability beliefstate-evaluate-belief-scenario-d21df308 -d '<json body>'
```

Example prompt: For belief ID 'btc-etf-approval-2025', evaluate the scenario where condition 'sec-approval' is met, 'institutional-adoption' is pending, and 'macro-risk' is not_triggered, as of 2025-06-01T00:00:00Z — what does BeliefState say about this thesis outcome?

## When to prefer this

Choose this endpoint when you already have a specific BeliefState belief_id and want to evaluate how that thesis resolves under a custom set of scenario assumptions. Ideal for AI trading agents or research automation pipelines that need to stress-test analyst theses against changing market conditions or hypothetical macro environments. Prefer this over general research lookup endpoints when you need scenario-specific conditional evaluation rather than raw thesis retrieval.

## Known failure modes

- Invalid belief_id returns an error or empty result if the thesis is not found in the BeliefState database
- Invalid condition_id within assumptions may return validation errors
- Malformed as_of datetime (not ISO 8601 UTC) will fail schema validation
- Providing more than 8 assumptions will be rejected by the schema
- Missing required fields (belief_id or scenario.assumptions) will cause a 400-level error
- Payment failure via x402 protocol will prevent the call from completing

## How this service works

The first AI-powered platform for top analyst research. Get theses from top analysts, dated evidence, and available outcomes for your AI.

## Output

A JSON envelope containing a schema_version, generated_at timestamp, and as_of timestamp, with the full evaluation of the belief scenario — indicating how the analyst thesis resolves given the provided condition statuses. The complete response schema is documented at the BeliefState endpoint and includes thesis outcomes, evidence alignment, and scenario-specific conclusions.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input",
  "output"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "belief_id",
      "scenario"
     ],
     "properties": {
      "as_of": {
       "type": "string",
       "format": "date-time",
       "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z))$"
      },
      "scenario": {
       "type": "object",
       "required": [
        "assumptions"
       ],
       "properties": {
        "assumptions": {
         "type": "array",
         "items": {
          "type": "object",
          "required": [
           "condition_id",
           "status"
          ],
          "properties": {
           "status": {
            "enum": [
             "pending",
             "met",
             "missed",
             "triggered",
             "not_triggered",
             "unknown"
            ],
            "type": "string"
           },
           "condition_id": {
            "type": "string",
            "maxLength": 128,
            "minLength": 1
           }
          },
          "additionalProperties": false
         },
         "maxItems": 8,
         "minItems": 1
        }
       },
       "additionalProperties": false
      },
      "belief_id": {
       "type": "string",
       "maxLength": 128,
       "minLength": 1
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "type": "string",
     "const": "POST"
    },
    "bodyType": {
     "type": "string",
     "const": "json"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type",
    "example"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "json"
    },
    "example": {
     "type": "object",
     "$comment": "Envelope excerpt only. Complete response schema: https://beliefstate.ai/v1/research/evaluate_belief_scenario?schema=output",
     "required": [
      "schema_version",
      "generated_at",
      "as_of"
     ],
     "properties": 
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "as_of": "2026-10-24T00:00:00.000Z",
  "generated_at": "2026-10-24T00:00:00.000Z",
  "schema_version": "1"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/beliefstate-evaluate-belief-scenario-d21df308/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from beliefstate.ai](https://www.zero.xyz/host/beliefstate.ai/llms.txt)