# TruthBear Gauge Calibrated > TruthBear Gauge Calibrated is a paid API for AI agents from api.truthbear.co, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-13). Returns calibrated, cross-station-comparable gauge readings for a given signal and entity, including normalized_index and pct_to_action metrics. ## Facts - Endpoint: GET https://api.truthbear.co/gauge/calibrated - Price: $0.005/call - Payment: x402 - Status: unknown - Last checked: 2026-09-13 - Activations on Zero: 0 - Tags: x402 - Canonical page: https://www.zero.xyz/c/truthbear-gauge-calibrated-f802aaa5 - Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_0fVhZEMc9agvjQ944n1ew 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-calibrated-f802aaa5 ``` Example prompt: What's the calibrated river level reading for gauge station 07010000 right now — I need the normalized_index and pct_to_action so I can compare it against other stations? ## When to prefer this Choose this endpoint when you need cross-station comparable gauge readings (normalized_index, pct_to_action) rather than raw values. Prefer this over raw gauge endpoints when comparing risk levels across different monitoring stations, or when you need an audit trail via the record_hash. Use the sibling gauge/history-series endpoint if you need a time series rather than the current point-in-time calibrated reading. If calibration is unavailable, you are not billed, making this safe to call speculatively. ## Known failure modes - 422 Unprocessable Entity with no_charge:true and reason:no-calibrated-for-this-line when calibration data is unavailable for the requested signal+entity combination — not billed - Missing or invalid signal_id returns an error (signal must be in genus.species format, e.g. hydrology.river-level) - Missing or invalid entity returns an error (entity must be a valid monitored object ID paired with the signal_id) - Entity not associated with the given signal_id returns an error or empty result ## How this service works Add-on, calibrated units: normalized_index and pct_to_action so readings compare across stations. When the line has no calibration basis you get 422 with no_charge:true and reason:no-calibrated-for-this-line, and are NOT billed. Every record carries an offline-recomputable record_hash. $0.0050 per call. ## Output Returns a JSON object with calibrated unit fields including normalized_index (cross-station comparable index value) and pct_to_action (how close the reading is to an action threshold), plus a record_hash for offline verification. If no calibration basis exists for the requested line, returns HTTP 422 with no_charge:true and reason:no-calibrated-for-this-line — and the call is not billed. ## Request schema (JSON Schema) ```json { "$schema": "https://json-schema.org/draft/2020-12/schema", "properties": { "input": { "type": "object", "properties": { "type": { "const": "http" }, "method": { "type": "string", "enum": [ "GET" ] }, "queryParams": { "type": "object", "additionalProperties": false, "properties": { "signal_id": { "type": "string", "description": "required - signal id (genus.species); free list at GET /gauge/catalog (paged; ?all=1 for every line)", "examples": [ "hydrology.river-level" ] }, "entity": { "type": "string", "description": "required - monitored object id, paired with signal_id; free list at GET /gauge/catalog?signal_id= -> signals[0].entities[]", "examples": [ "07010000" ] } }, "required": [ "signal_id", "entity" ] } }, "required": [ "type", "method", "queryParams" ] }, "output": { "type": "object", "properties": { "type": { "const": "json" }, "example": {} }, "required": [ "type" ] } } } ``` ## Response schema (JSON Schema) ```json { "type": "json", "example": { "dim": "calibrated", "grade": "screening-level, not decision-grade", "scope": { "full": "https://api.truthbear.co/scope/v1", "verifiability": "via-endpoint", "monitoring_not_forecast": true, "intelligence_not_command": true }, "entity": "07010000", "nature": "This API supplies data organisation and trend description only. It is not a recommendation to act; the decision is yours. Purely descriptive - no judgement, no prediction. Official source plus record_hash; verify with the free /gauge/verify.", "signal_id": "hydrology.river-level", "calibrated": { "band": "below_action", "unit": "ft", "scale": "flood_stage", "metric": "gauge_height_ft", "index_basis": "normalized_index: piecewise linear (action=0/minor=1/moderate=2/major=3); below the first band = (value - first threshold) / first threshold, clamped to [-1,0); above the top band it is unbounded. pct_to_action = value / first alert threshold (bounded, 1 = at the first alert)", "current_value": 6.48, "pct_to_action": 0.231, "normalized_index": -0.769 }, "provenance": { "freshness": "fresh", "age_hours_now": 5.5, "freshness_basis": "cadence=daily; fresh<=24h; recent<=192h; dead_source>1440h; age_basis=request-time(now minus observed_at)" }, "source_ref": "https://waterdata.usgs.gov/monitoring-location/07010000/", "entity_name": "Mississippi River at St. Louis, MO", "observed_at": "2026-08-26T09:30:00.000Z", "record_hash": "sha256:a3986d8689a1d9f6e8b4b92c2318d5af64291cdedbdbd3d706e0049e16fcb42e", "record_hash_verifiable": { "mode": "via-endpoint", "note": "This response is a projected delivery (some core fields are omitted to control size). Cross-check record_hash with the free /gauge/verify, or buy /gauge to get the complete core for offline recomputation." } } } ``` ## More - Live health (JSON, refreshed every minute): https://www.zero.xyz/c/truthbear-gauge-calibrated-f802aaa5/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)