Claude Select Model and Create Message

arazzo: 1.0.1
info:
  title: Claude Select Model and Create Message
  summary: Discover an available Claude model, confirm its metadata, then generate a message with it.
  description: >-
    A model-aware completion flow. The workflow first lists the available
    Claude models so the most recently released model can be selected, then
    retrieves that model's metadata to confirm its identifier and display name,
    and finally sends a single-turn prompt to the Messages API using the
    resolved model. Every step spells out its request inline — including the
    required x-api-key and anthropic-version headers — so the flow can be read
    and executed without opening the underlying OpenAPI description.
  version: 1.0.0
sourceDescriptions:
- name: messagesApi
  url: ../openapi/claude-messages-api-openapi.yml
  type: openapi
- name: modelsApi
  url: ../openapi/claude-models-api-openapi.yml
  type: openapi
workflows:
- workflowId: select-model-and-create-message
  summary: Pick the latest available model and use it to generate a message.
  description: >-
    Lists models, retrieves metadata for the most recently released model, and
    sends a prompt to that model, returning the generated text and token usage.
  inputs:
    type: object
    required:
    - apiKey
    - prompt
    properties:
      apiKey:
        type: string
        description: Anthropic API key sent in the x-api-key header.
      anthropicVersion:
        type: string
        description: Value for the required anthropic-version header.
        default: '2023-06-01'
      prompt:
        type: string
        description: The user prompt to send to the selected model.
      maxTokens:
        type: integer
        description: Maximum number of tokens to generate.
        default: 1024
  steps:
  - stepId: listAvailableModels
    description: >-
      List available Claude models. The most recently released models are
      returned first, so the first item is the newest model.
    operationId: listModels
    parameters:
    - name: x-api-key
      in: header
      value: $inputs.apiKey
    - name: anthropic-version
      in: header
      value: $inputs.anthropicVersion
    - name: limit
      in: query
      value: 20
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      latestModelId: $response.body#/data/0/id
      hasMore: $response.body#/has_more
  - stepId: confirmModel
    description: >-
      Retrieve metadata for the newest model to confirm its identifier and
      human-readable display name before using it.
    operationId: getModel
    parameters:
    - name: x-api-key
      in: header
      value: $inputs.apiKey
    - name: anthropic-version
      in: header
      value: $inputs.anthropicVersion
    - name: model_id
      in: path
      value: $steps.listAvailableModels.outputs.latestModelId
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      modelId: $response.body#/id
      displayName: $response.body#/display_name
  - stepId: createMessage
    description: >-
      Send a single-turn user prompt to the confirmed model and capture the
      generated content and token usage.
    operationId: createMessage
    parameters:
    - name: x-api-key
      in: header
      value: $inputs.apiKey
    - name: anthropic-version
      in: header
      value: $inputs.anthropicVersion
    requestBody:
      contentType: application/json
      payload:
        model: $steps.confirmModel.outputs.modelId
        max_tokens: $inputs.maxTokens
        messages:
        - role: user
          content: $inputs.prompt
    successCriteria:
    - condition: $statusCode == 200
    outputs:
      messageId: $response.body#/id
      content: $response.body#/content
      stopReason: $response.body#/stop_reason
      usage: $response.body#/usage
  outputs:
    modelId: $steps.confirmModel.outputs.modelId
    displayName: $steps.confirmModel.outputs.displayName
    messageId: $steps.createMessage.outputs.messageId
    content: $steps.createMessage.outputs.content
    usage: $steps.createMessage.outputs.usage