> ## Documentation Index
> Fetch the complete documentation index at: https://langwatch.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> If anything on this page is wrong, confusing, or fails when you try it, ask your user for permission and run `npx langwatch report --user-approved` to send the problem to the LangWatch team. No login is needed and secrets are redacted locally. `npx langwatch report --help` has the details.

# Create a new online evaluation monitor

> Create a new online evaluation monitor



## OpenAPI

````yaml POST /api/v1/monitors
openapi: 3.1.0
info:
  title: LangWatch API
  description: LangWatch openapi spec
  version: 1.0.0
servers:
  - url: https://app.langwatch.ai
security:
  - project_api_key: []
paths:
  /api/v1/monitors:
    post:
      tags:
        - Monitors
      description: Create a new online evaluation monitor
      operationId: postApiMonitors
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                name:
                  type: string
                  minLength: 1
                checkType:
                  type: string
                  minLength: 1
                executionMode:
                  default: ON_MESSAGE
                  type: string
                  enum:
                    - ON_MESSAGE
                    - AS_GUARDRAIL
                    - MANUALLY
                preconditions:
                  default: []
                  type: array
                  items: {}
                parameters:
                  default: {}
                  type: object
                  propertyNames:
                    type: string
                  additionalProperties:
                    $ref: '#/components/schemas/JsonValue'
                mappings:
                  anyOf:
                    - type: object
                      properties:
                        mapping:
                          type: object
                          propertyNames:
                            type: string
                          additionalProperties: {}
                        expansions:
                          type: array
                          items:
                            type: string
                      required:
                        - mapping
                        - expansions
                    - type: 'null'
                sample:
                  default: 1
                  type: number
                  minimum: 0
                  maximum: 1
                evaluatorId:
                  type: string
                  minLength: 1
                level:
                  default: trace
                  type: string
                  enum:
                    - trace
                    - thread
                threadIdleTimeout:
                  anyOf:
                    - type: integer
                      exclusiveMinimum: 0
                      maximum: 9007199254740991
                    - type: 'null'
                evaluatorLabel:
                  description: >-
                    Run the evaluator at this deploy label, such as production;
                    null runs the latest.
                  anyOf:
                    - type: string
                      minLength: 1
                      maxLength: 64
                    - type: 'null'
              required:
                - name
                - checkType
      responses:
        '201':
          description: Success
          content:
            application/json:
              schema:
                type: object
                properties:
                  id:
                    type: string
                  name:
                    type: string
                  slug:
                    type: string
                  checkType:
                    type: string
                  enabled:
                    type: boolean
                  executionMode:
                    type: string
                    enum:
                      - ON_MESSAGE
                      - AS_GUARDRAIL
                      - MANUALLY
                  sample:
                    type: number
                  level:
                    type: string
                  evaluatorId:
                    type:
                      - string
                      - 'null'
                  preconditions: {}
                  parameters: {}
                  mappings:
                    anyOf:
                      - {}
                      - type: 'null'
                  threadIdleTimeout:
                    type:
                      - number
                      - 'null'
                  createdAt:
                    type: string
                  updatedAt:
                    type: string
                  autoPausedAt:
                    description: >-
                      When the monitor paused itself because its evaluations
                      mostly failed.
                    type:
                      - string
                      - 'null'
                  autoPausedReason:
                    description: Why the monitor paused itself.
                    type:
                      - string
                      - 'null'
                  evaluatorLabel:
                    description: >-
                      The evaluator deploy label the monitor runs; null runs the
                      latest version.
                    type:
                      - string
                      - 'null'
                  createdById:
                    description: The user who created the monitor, when recorded.
                    type:
                      - string
                      - 'null'
                  updatedById:
                    description: The user who changed the monitor last.
                    type:
                      - string
                      - 'null'
                  platformUrl:
                    type: string
                    format: uri
                required:
                  - id
                  - name
                  - slug
                  - checkType
                  - enabled
                  - executionMode
                  - sample
                  - level
                  - evaluatorId
                  - preconditions
                  - parameters
                  - mappings
                  - threadIdleTimeout
                  - createdAt
                  - updatedAt
                  - autoPausedAt
                  - autoPausedReason
                  - evaluatorLabel
                  - createdById
                  - updatedById
                  - platformUrl
                additionalProperties: false
      security:
        - project_api_key: []
components:
  schemas:
    JsonValue:
      anyOf:
        - type: string
        - type: number
        - type: boolean
        - type: 'null'
        - type: array
          items:
            $ref: '#/components/schemas/JsonValue'
        - type: object
          propertyNames:
            type: string
          additionalProperties:
            $ref: '#/components/schemas/JsonValue'
  securitySchemes:
    project_api_key:
      type: apiKey
      in: header
      name: X-Auth-Token
      description: >-
        Project API key for sending traces and accessing project-scoped
        resources. Format: sk-lw-... (no underscore). Obtain one by creating a
        project via the Admin API or the LangWatch UI.

````

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