# TruthBear Gauge Historical Placement Add-on

> TruthBear Gauge Historical Placement Add-on is a paid API for AI agents from api.truthbear.co, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Returns the seasonal percentile placement (and supporting stats) for the current reading of a monitored signal and entity — descriptive context, not a forecast.

## Facts

- Endpoint: GET https://api.truthbear.co/gauge/history
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/truthbear-gauge-historical-placement-add-on-041cdcd2
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-GmXkR2972jAbnadxm6l7

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 truthbear-gauge-historical-placement-add-on-041cdcd2
```

Example prompt: What seasonal percentile is the current river level reading at gauge 07010000 for the hydrology.river-level signal — and show me the percentile table and how it was computed?

## When to prefer this

Choose this endpoint when you need to contextualize a current signal reading against its historical seasonal distribution — specifically to understand whether a reading is unusually high, low, or typical for the time of year. Prefer it over raw time-series exports (gauge/history-series) when you only need the current placement summary rather than the full historical dataset. Use it as an enrichment layer alongside live readings or calibrated index data (gauge/calibrated) to add statistical depth.

## Known failure modes

- 422 no_charge: no historical data exists for the given signal_id and entity combination — not billed
- Missing required query parameter signal_id or entity returns validation error
- Invalid signal_id format (must follow genus.species convention) causes rejection
- Entity ID not recognized for the provided signal_id — returns empty or error
- Endpoint is descriptive only; asking for forecasts or advice will not yield meaningful results

## How this service works

Add-on, historical placement: seasonal percentile for the current point, frequency, the percentile table, and the method and source used to compute them. Descriptive only, never a forecast or advice. No data -> 422 no_charge, not billed. $0.0050 per call.

## Output

A JSON object containing the seasonal percentile for the current reading, the frequency of that reading historically, a full percentile table for context, and metadata describing the method and source used to compute the placement. Returns a 422 no_charge error (unbilled) when no data is available for the requested signal and entity.

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "queryParams"
   ],
   "properties": {
    "type": {
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "signal_id",
      "entity"
     ],
     "properties": {
      "entity": {
       "type": "string",
       "examples": [
        "07010000"
       ],
       "description": "required - monitored object id, paired with signal_id; free list at GET /gauge/catalog?signal_id=<signal_id> -> signals[0].entities[]"
      },
      "signal_id": {
       "type": "string",
       "examples": [
        "hydrology.river-level"
       ],
       "description": "required - signal id (genus.species); free list at GET /gauge/catalog (paged; ?all=1 for every line)"
      }
     },
     "additionalProperties": false
    }
   }
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "const": "json"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/truthbear-gauge-historical-placement-add-on-041cdcd2/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.truthbear.co](https://www.zero.xyz/host/api.truthbear.co/llms.txt)