Models, errors and the sync client

Claude Models API

val modelsRequest = client.listModels()
val models = modelsRequest.send(backend)

models match {
  case Right(response) =>
    response.data.foreach(model => println(s"${model.id} - ${model.displayName.getOrElse("N/A")}"))
  case Left(error) =>
    println(s"Error: $error")
}

Common Claude models (use listModels() for current list):

claude-3-sonnet-20240229 - Balanced performance and speed
claude-3-opus-20240229 - Highest capability model
claude-3-haiku-20240307 - Fastest model
claude-instant-1.2 - Legacy fast model

Claude Error Handling

Claude-specific exception hierarchy:

import sttp.ai.claude.ClaudeExceptions.*

client.createMessage(request).send(backend) match {
  case Right(response) => // Success
    handleResponse(response)
  case Left(error) => error match {
    case _: AuthenticationException => // Invalid API key
      println("Authentication failed - check your API key")
    case _: RateLimitException => // Rate limited
      println("Rate limited - please wait before retrying")
    case _: InvalidRequestException => // Malformed request
      println("Invalid request - check your parameters")
    case _: PermissionException => // Access denied
      println("Permission denied for this resource")
    case _: APIException => // Other API error
      println(s"API error: ${error.getMessage}")
    case _: DeserializationClaudeException => // JSON parsing error
      println("Failed to parse response")
  }
}

Key Differences from OpenAI API

Feature	Claude API	OpenAI API
Message Content	`ContentBlock` arrays	Simple strings
System Messages	`system` parameter	Role-based message
Authentication	`x-api-key` + `anthropic-version` headers	`Authorization` header
Image Input	ContentBlock with base64	URL or base64 in content
Tool Calling	Native tool structure	Function calling
Streaming	Server-Sent Events	Server-Sent Events
Model Names	`claude-3-sonnet-20240229`	`gpt-4`

Synchronous Claude Client

For blocking operations, use ClaudeSyncClient:

import sttp.ai.claude.ClaudeSyncClient

val syncClient = new ClaudeSyncClient(config)

// Throws ClaudeException on error
try {
  val response = syncClient.createMessage(request)
  println(response.content.head.text.getOrElse(""))
} catch {
  case e: ClaudeException => println(s"Error: ${e.getMessage}")
}