feat(anthropic): update model params + better max_token handling

rig-core/examples/anthropic_agent.rs

@@ -18,7 +18,6 @@ async fn main() -> Result<(), anyhow::Error> {
         .agent(CLAUDE_3_5_SONNET)
         .preamble("Be precise and concise.")
         .temperature(0.5)
-        .max_tokens(8192)
         .build();
 
     // Prompt the agent and print the response

rig-core/src/providers/anthropic/completion.rs

@@ -15,11 +15,14 @@ use super::client::Client;
 // ================================================================
 // Anthropic Completion API
 // ================================================================
-/// `claude-3-5-sonnet-20240620` completion model
-pub const CLAUDE_3_5_SONNET: &str = "claude-3-5-sonnet-20240620";
+/// `claude-3-5-sonnet-latest` completion model
+pub const CLAUDE_3_5_SONNET: &str = "claude-3-5-sonnet-latest";
 
-/// `claude-3-5-haiku-20240620` completion model
-pub const CLAUDE_3_OPUS: &str = "claude-3-opus-20240229";
+/// `claude-3-5-haiku-latest` completion model
+pub const CLAUDE_3_5_HAIKU: &str = "claude-3-5-haiku-latest";
+
+/// `claude-3-5-haiku-latest` completion model
+pub const CLAUDE_3_OPUS: &str = "claude-3-opus-latest";
 
 /// `claude-3-sonnet-20240229` completion model
 pub const CLAUDE_3_SONNET: &str = "claude-3-sonnet-20240229";
@@ -139,17 +142,37 @@ impl From<completion::Message> for Message {
 pub struct CompletionModel {
     client: Client,
     pub model: String,
+    default_max_tokens: Option<u64>,
 }
 
 impl CompletionModel {
     pub fn new(client: Client, model: &str) -> Self {
         Self {
             client,
             model: model.to_string(),
+            default_max_tokens: calculate_max_tokens(model),
         }
     }
 }
 
+/// Anthropic requires a `max_tokens` parameter to be set, which is dependant on the model. If not
+/// set or if set too high, the request will fail. The following values are based on the models
+/// available at the time of writing.
+///
+/// Dev Note: This is really bad design, I'm not sure why they did it like this..
+fn calculate_max_tokens(model: &str) -> Option<u64> {
+    if model.starts_with("claude-3-5-sonnet") || model.starts_with("claude-3-5-haiku") {
+        Some(8192)
+    } else if model.starts_with("claude-3-opus")
+        || model.starts_with("claude-3-sonnet")
+        || model.starts_with("claude-3-haiku")
+    {
+        Some(4096)
+    } else {
+        None
+    }
+}
+
 #[derive(Debug, Deserialize, Serialize)]
 struct Metadata {
     user_id: Option<String>,
@@ -177,11 +200,15 @@ impl completion::CompletionModel for CompletionModel {
         let prompt_with_context = completion_request.prompt_with_context();
 
         // Check if max_tokens is set, required for Anthropic
-        if completion_request.max_tokens.is_none() {
+        let max_tokens = if let Some(tokens) = completion_request.max_tokens {
+            tokens
+        } else if let Some(tokens) = self.default_max_tokens {
+            tokens
+        } else {
             return Err(CompletionError::RequestError(
-                "max_tokens must be set for Anthropic".into(),
+                "`max_tokens` must be set for Anthropic".into(),
             ));
-        }
+        };
 
         let mut request = json!({
             "model": self.model,
@@ -194,7 +221,7 @@ impl completion::CompletionModel for CompletionModel {
                     content: prompt_with_context,
                 }))
                 .collect::<Vec<_>>(),
-            "max_tokens": completion_request.max_tokens,
+            "max_tokens": max_tokens,
             "system": completion_request.preamble.unwrap_or("".to_string()),
         });