FIX: Correctly pass tool_choice when using Claude models. (#1364)

The `ClaudePrompt` object couldn't access the original prompt's tool_choice attribute, affecting both Anthropic and Bedrock.

Author: romanrizzi

lib/completions/dialects/claude.rb

@@ -13,14 +13,13 @@ def can_translate?(llm_model)
         end
 
         class ClaudePrompt
-          attr_reader :system_prompt
-          attr_reader :messages
-          attr_reader :tools
+          attr_reader :system_prompt, :messages, :tools, :tool_choice
 
-          def initialize(system_prompt, messages, tools)
+          def initialize(system_prompt, messages, tools, tool_choice)
             @system_prompt = system_prompt
             @messages = messages
             @tools = tools
+            @tool_choice = tool_choice
           end
 
           def has_tools?
@@ -55,7 +54,7 @@ def translate
           tools = nil
           tools = tools_dialect.translated_tools if native_tool_support?
 
-          ClaudePrompt.new(system_prompt.presence, interleving_messages, tools)
+          ClaudePrompt.new(system_prompt.presence, interleving_messages, tools, tool_choice)
         end
 
         def max_prompt_tokens

spec/lib/completions/endpoints/anthropic_spec.rb

@@ -770,6 +770,55 @@
     end
   end
 
+  describe "forced tool use" do
+    it "can properly force tool use" do
+      prompt =
+        DiscourseAi::Completions::Prompt.new(
+          "You are a bot",
+          messages: [type: :user, id: "user1", content: "echo hello"],
+          tools: [echo_tool],
+          tool_choice: "echo",
+        )
+
+      response_body = {
+        id: "msg_01RdJkxCbsEj9VFyFYAkfy2S",
+        type: "message",
+        role: "assistant",
+        model: "claude-3-haiku-20240307",
+        content: [
+          {
+            type: "tool_use",
+            id: "toolu_bdrk_014CMjxtGmKUtGoEFPgc7PF7",
+            name: "echo",
+            input: {
+              text: "hello",
+            },
+          },
+        ],
+        stop_reason: "end_turn",
+        stop_sequence: nil,
+        usage: {
+          input_tokens: 345,
+          output_tokens: 65,
+        },
+      }.to_json
+
+      parsed_body = nil
+      stub_request(:post, url).with(
+        body:
+          proc do |req_body|
+            parsed_body = JSON.parse(req_body, symbolize_names: true)
+            true
+          end,
+      ).to_return(status: 200, body: response_body)
+
+      llm.generate(prompt, user: Discourse.system_user)
+
+      # Verify that tool_choice: "echo" is present
+      expect(parsed_body.dig(:tool_choice, :name)).to eq("echo")
+    end
+  end
+
   describe "structured output via prefilling" do
     it "forces the response to be a JSON and using the given JSON schema" do
       schema = {

spec/lib/completions/endpoints/aws_bedrock_spec.rb

@@ -547,6 +547,67 @@ def encode_message(message)
     end
   end
 
+  describe "forced tool use" do
+    it "can properly force tool use" do
+      proxy = DiscourseAi::Completions::Llm.proxy("custom:#{model.id}")
+      request = nil
+
+      tools = [
+        {
+          name: "echo",
+          description: "echo something",
+          parameters: [
+            { name: "text", type: "string", description: "text to echo", required: true },
+          ],
+        },
+      ]
+
+      prompt =
+        DiscourseAi::Completions::Prompt.new(
+          "You are a bot",
+          messages: [type: :user, id: "user1", content: "echo hello"],
+          tools: tools,
+          tool_choice: "echo",
+        )
+
+      # Mock response from Bedrock
+      content = {
+        content: [
+          {
+            type: "tool_use",
+            id: "toolu_bdrk_014CMjxtGmKUtGoEFPgc7PF7",
+            name: "echo",
+            input: {
+              text: "hello",
+            },
+          },
+        ],
+        usage: {
+          input_tokens: 25,
+          output_tokens: 15,
+        },
+      }.to_json
+
+      stub_request(
+        :post,
+        "https://bedrock-runtime.us-east-1.amazonaws.com/model/anthropic.claude-3-sonnet-20240229-v1:0/invoke",
+      )
+        .with do |inner_request|
+          request = inner_request
+          true
+        end
+        .to_return(status: 200, body: content)
+
+      proxy.generate(prompt, user: user)
+
+      # Parse the request body
+      request_body = JSON.parse(request.body)
+
+      # Verify that tool_choice: "echo" is present
+      expect(request_body.dig("tool_choice", "name")).to eq("echo")
+    end
+  end
+
   describe "structured output via prefilling" do
     it "forces the response to be a JSON and using the given JSON schema" do
       schema = {