> ## Documentation Index > Fetch the complete documentation index at: https://docs.coval.ai/llms.txt > Use this file to discover all available pages before exploring further. # Create metric baseline > Create a new anomaly-detection baseline for a specific metric. ## OpenAPI ````yaml /api-reference/v1/metrics-v1.yaml post /metrics/{metric_id}/baselines openapi: 3.0.3 info: title: Coval Metrics API version: 1.0.0 description: | Manage custom evaluation metrics for agent testing and monitoring. contact: name: Coval API Support email: support@coval.dev url: https://docs.coval.ai license: name: Proprietary url: https://coval.dev/terms servers: - url: https://api.coval.dev/v1 description: Production API security: - ApiKeyAuth: [] tags: - name: Metrics description: CRUD operations for custom evaluation metrics paths: /metrics/{metric_id}/baselines: post: tags: - Metrics summary: Create metric baseline description: Create a new anomaly-detection baseline for a specific metric. operationId: createMetricBaseline parameters: - name: metric_id in: path required: true schema: type: string pattern: ^[a-zA-Z0-9]{22}$ description: 22-character metric ID requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateMetricBaselineRequest' examples: ewmaBaseline: summary: EWMA baseline (above-threshold anomalies) value: agent_id: gk3jK9mPq2xRt5vW8yZaBc test_set_id: 01HXKZ4M5N6P7Q8R9TESTSET01 display_name: Resolution rate baseline status: ACTIVE detection_method: EWMA sigma_threshold: 2.5 direction: ABOVE config: time_constant_seconds: 604800 monitoringBaseline: summary: Monitoring baseline (no test set) value: agent_id: gk3jK9mPq2xRt5vW8yZaBc display_name: Production sentiment baseline status: STANDBY sigma_threshold: 3 direction: BOTH responses: '201': description: Baseline created successfully content: application/json: schema: $ref: '#/components/schemas/Baseline' examples: ewmaBaseline: summary: Newly created EWMA baseline value: ulid: 01HXKZ4M5N6P7Q8R9STVWXYZAB metric_id: abc123def456ghi789jklm agent_id: gk3jK9mPq2xRt5vW8yZaBc test_set_id: 01HXKZ4M5N6P7Q8R9TESTSET01 persona_id: null display_name: Resolution rate baseline status: ACTIVE detection_method: EWMA baseline_float: null baseline_sigma: null observation_count: 0 sigma_threshold: 2.5 direction: ABOVE sigma_bands: null last_processed_run_completed_at: null created_at: '2026-04-23T17:00:00Z' last_updated_at: '2026-04-23T17:00:00Z' '400': description: Validation error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '401': $ref: '#/components/responses/Unauthorized' '404': $ref: '#/components/responses/NotFound' '500': $ref: '#/components/responses/InternalError' components: schemas: CreateMetricBaselineRequest: type: object description: Request body for creating a baseline. All fields optional. properties: agent_id: type: string nullable: true description: Agent ID. Null for org-wide baselines. test_set_id: type: string nullable: true description: Test set ULID. Null for monitoring. persona_id: type: string nullable: true description: Persona ULID. Null when the baseline covers all personas. display_name: type: string nullable: true maxLength: 200 description: User-facing label. status: allOf: - $ref: '#/components/schemas/BaselineStatus' description: Initial status. Defaults to STANDBY. detection_method: allOf: - $ref: '#/components/schemas/BaselineDetectionMethod' description: Algorithm. Defaults to EWMA. sigma_threshold: type: number nullable: true minimum: 0 exclusiveMinimum: true description: >- Sigmas from the baseline that constitute an anomaly. Defaults to 2.0. direction: allOf: - $ref: '#/components/schemas/BaselineDirection' description: >- Which direction(s) of deviation count as anomalous. Defaults to BOTH. config: allOf: - $ref: '#/components/schemas/BaselineConfig' Baseline: type: object description: Anomaly-detection baseline for a metric. required: - ulid - status - detection_method - sigma_threshold - direction - created_at - last_updated_at properties: ulid: type: string description: Baseline ULID. example: 01HXKZ4M5N6P7Q8R9STVWXYZAB metric_id: type: string nullable: true description: Metric ULID. agent_id: type: string nullable: true description: Agent ID. Null for org-wide baselines. test_set_id: type: string nullable: true description: Test set ULID. Null for monitoring. persona_id: type: string nullable: true description: Persona ULID. Null when the baseline covers all personas. display_name: type: string nullable: true description: User-facing label. status: $ref: '#/components/schemas/BaselineStatus' detection_method: $ref: '#/components/schemas/BaselineDetectionMethod' baseline_float: type: number nullable: true description: Current baseline mean estimate. baseline_sigma: type: number nullable: true description: Current baseline standard deviation estimate. observation_count: type: integer default: 0 description: Number of observations processed. sigma_threshold: type: number description: Sigmas from the baseline that constitute an anomaly. direction: $ref: '#/components/schemas/BaselineDirection' sigma_bands: type: object nullable: true additionalProperties: type: number description: > Computed sigma bands keyed by level (e.g. `upper_1sigma`, `lower_2sigma`, `upper_2sigma`). Null when baseline stats are not yet populated. Levels controlled by the `sigma_levels` query param. last_processed_run_completed_at: type: string format: date-time nullable: true description: 'Cursor: when the last processed run completed.' created_at: type: string format: date-time last_updated_at: type: string format: date-time ErrorResponse: type: object required: - error properties: error: type: object required: - code - message properties: code: type: string enum: - INVALID_ARGUMENT - UNAUTHENTICATED - PERMISSION_DENIED - NOT_FOUND - ALREADY_EXISTS - INTERNAL message: type: string details: type: array items: type: object properties: field: type: string nullable: true description: type: string BaselineStatus: type: string description: Baseline lifecycle status. enum: - ACTIVE - STANDBY - ARCHIVED BaselineDetectionMethod: type: string description: Anomaly detection algorithm. Currently only EWMA. enum: - EWMA BaselineDirection: type: string description: Which direction(s) of deviation count as anomalous. enum: - BOTH - ABOVE - BELOW BaselineConfig: type: object description: >- Algorithm-specific configuration. Currently only the EWMA detector is supported. properties: time_constant_seconds: type: integer default: 604800 description: >- EWMA time constant in seconds; controls decay rate. Default 604800 (7 days). responses: Unauthorized: description: Authentication failed content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: UNAUTHENTICATED message: Authentication failed details: - field: X-API-Key description: Invalid or missing API key NotFound: description: Resource not found content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: NOT_FOUND message: Metric not found details: - field: metric_id description: No metric found with this ID InternalError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: INTERNAL message: Internal server error securitySchemes: ApiKeyAuth: type: apiKey in: header name: X-API-Key description: API key for authentication ````