diff --git a/docs/_core_features/tools.md b/docs/_core_features/tools.md
index 46e0297d7..fcffd4b02 100644
--- a/docs/_core_features/tools.md
+++ b/docs/_core_features/tools.md
@@ -188,6 +188,38 @@ puts response.content
 # => "Current weather at 52.52, 13.4: Temperature: 12.5°C, Wind Speed: 8.3 km/h, Conditions: Mainly clear, partly cloudy, and overcast."
 ```
 
+### Tool Choice Control
+
+Control when and how tools are called using `choice` and `parallel` options.
+
+```ruby
+chat = RubyLLM.chat(model: 'gpt-4o')
+
+# Basic usage with defaults
+chat.with_tools(Weather, Calculator)  # uses provider defaults
+
+# Force tool usage, one at a time
+chat.with_tools(Weather, Calculator, choice: :required, parallel: false)
+
+# Force specific tool
+chat.with_tool(Weather, choice: :weather, parallel: true)
+```
+
+**Parameter Values:**
+- **`choice`**: Controls tool choice behavior
+  - `:auto` Model decides whether to use any tools
+  - `:required` - Model must use one of the provided tools
+  - `:none` - Disable all tools
+  - `"tool_name"` - Force a specific tool (e.g., `:weather` for `Weather` tool)
+- **`parallel`**: Controls parallel tool calls
+  - `true` Allow multiple tool calls simultaneously
+  - `false` - One at a time
+
+If not provided, RubyLLM will use the provider's default behavior for tool choice and parallel tool calls.
+
+> With `:required` or specific tool choices, the tool_choice is automatically reset to `nil` after tool execution to prevent infinite loops.
+{: .note }
+
 ### Model Compatibility
 
 RubyLLM will attempt to use tools with any model. If the model doesn't support function calling, the provider will return an appropriate error when you call `ask`.
diff --git a/lib/ruby_llm/chat.rb b/lib/ruby_llm/chat.rb
index 6b5b94daa..ad6f0b6b6 100644
--- a/lib/ruby_llm/chat.rb
+++ b/lib/ruby_llm/chat.rb
@@ -5,7 +5,7 @@ module RubyLLM
   class Chat
     include Enumerable
 
-    attr_reader :model, :messages, :tools, :params, :headers, :schema
+    attr_reader :model, :messages, :tools, :tool_prefs, :params, :headers, :schema
 
     def initialize(model: nil, provider: nil, assume_model_exists: false, context: nil)
       if assume_model_exists && !provider
@@ -19,6 +19,7 @@ def initialize(model: nil, provider: nil, assume_model_exists: false, context: n
       @temperature = nil
       @messages = []
       @tools = {}
+      @tool_prefs = { choice: nil, parallel: nil }
       @params = {}
       @headers = {}
       @schema = nil
@@ -44,15 +45,19 @@ def with_instructions(instructions, replace: false)
       self
     end
 
-    def with_tool(tool)
-      tool_instance = tool.is_a?(Class) ? tool.new : tool
-      @tools[tool_instance.name.to_sym] = tool_instance
+    def with_tool(tool, choice: nil, parallel: nil)
+      unless tool.nil?
+        tool_instance = tool.is_a?(Class) ? tool.new : tool
+        @tools[tool_instance.name.to_sym] = tool_instance
+      end
+      update_tool_options(choice:, parallel:)
       self
     end
 
-    def with_tools(*tools, replace: false)
+    def with_tools(*tools, replace: false, choice: nil, parallel: nil)
       @tools.clear if replace
       tools.compact.each { |tool| with_tool tool }
+      update_tool_options(choice:, parallel:)
       self
     end
 
@@ -125,6 +130,7 @@ def complete(&) # rubocop:disable Metrics/PerceivedComplexity
       response = @provider.complete(
         messages,
         tools: @tools,
+        tool_prefs: @tool_prefs,
         temperature: @temperature,
         model: @model,
         params: @params,
@@ -200,6 +206,7 @@ def handle_tool_calls(response, &) # rubocop:disable Metrics/PerceivedComplexity
         halt_result = result if result.is_a?(Tool::Halt)
       end
 
+      reset_tool_choice if forced_tool_choice?
       halt_result || complete(&)
     end
 
@@ -208,5 +215,27 @@ def execute_tool(tool_call)
       args = tool_call.arguments
       tool.call(args)
     end
+
+    def update_tool_options(choice:, parallel:)
+      unless choice.nil?
+        valid_tool_choices = %i[auto none required] + tools.keys
+        unless valid_tool_choices.include?(choice.to_sym)
+          raise InvalidToolChoiceError,
+                "Invalid tool choice: #{choice}. Valid choices are: #{valid_tool_choices.join(', ')}"
+        end
+
+        @tool_prefs[:choice] = choice.to_sym
+      end
+
+      @tool_prefs[:parallel] = !!parallel unless parallel.nil?
+    end
+
+    def forced_tool_choice?
+      @tool_prefs[:choice] && !%i[auto none].include?(@tool_prefs[:choice])
+    end
+
+    def reset_tool_choice
+      @tool_prefs[:choice] = nil
+    end
   end
 end
diff --git a/lib/ruby_llm/error.rb b/lib/ruby_llm/error.rb
index 3908bee27..92c96120b 100644
--- a/lib/ruby_llm/error.rb
+++ b/lib/ruby_llm/error.rb
@@ -15,6 +15,7 @@ def initialize(response = nil, message = nil)
   # Error classes for non-HTTP errors
   class ConfigurationError < StandardError; end
   class InvalidRoleError < StandardError; end
+  class InvalidToolChoiceError < StandardError; end
   class ModelNotFoundError < StandardError; end
   class UnsupportedAttachmentError < StandardError; end
 
diff --git a/lib/ruby_llm/provider.rb b/lib/ruby_llm/provider.rb
index f3344e57d..d62a82817 100644
--- a/lib/ruby_llm/provider.rb
+++ b/lib/ruby_llm/provider.rb
@@ -37,13 +37,16 @@ def configuration_requirements
       self.class.configuration_requirements
     end
 
-    def complete(messages, tools:, temperature:, model:, params: {}, headers: {}, schema: nil, &) # rubocop:disable Metrics/ParameterLists
+    # rubocop:disable Metrics/ParameterLists
+    def complete(messages, tools:, temperature:, model:, params: {}, headers: {}, schema: nil,
+                 tool_prefs: nil, &)
       normalized_temperature = maybe_normalize_temperature(temperature, model)
 
       payload = Utils.deep_merge(
         render_payload(
           messages,
           tools: tools,
+          tool_prefs: tool_prefs,
           temperature: normalized_temperature,
           model: model,
           stream: block_given?,
@@ -58,6 +61,7 @@ def complete(messages, tools:, temperature:, model:, params: {}, headers: {}, sc
         sync_response @connection, payload, headers
       end
     end
+    # rubocop:enable Metrics/ParameterLists
 
     def list_models
       response = @connection.get models_url
diff --git a/lib/ruby_llm/providers/anthropic/capabilities.rb b/lib/ruby_llm/providers/anthropic/capabilities.rb
index 710b55386..fdf86924c 100644
--- a/lib/ruby_llm/providers/anthropic/capabilities.rb
+++ b/lib/ruby_llm/providers/anthropic/capabilities.rb
@@ -34,6 +34,14 @@ def supports_functions?(model_id)
           model_id.match?(/claude-3/)
         end
 
+        def supports_tool_choice?(_model_id)
+          true
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          true
+        end
+
         def supports_json_mode?(model_id)
           model_id.match?(/claude-3/)
         end
diff --git a/lib/ruby_llm/providers/anthropic/chat.rb b/lib/ruby_llm/providers/anthropic/chat.rb
index 85630b0c1..e08e3e7d8 100644
--- a/lib/ruby_llm/providers/anthropic/chat.rb
+++ b/lib/ruby_llm/providers/anthropic/chat.rb
@@ -11,14 +11,17 @@ def completion_url
           '/v1/messages'
         end
 
-        def render_payload(messages, tools:, temperature:, model:, stream: false, schema: nil) # rubocop:disable Metrics/ParameterLists,Lint/UnusedMethodArgument
+        # rubocop:disable Metrics/ParameterLists,Lint/UnusedMethodArgument
+        def render_payload(messages, tools:, tool_prefs:,
+                           temperature:, model:, stream: false, schema: nil)
           system_messages, chat_messages = separate_messages(messages)
           system_content = build_system_content(system_messages)
 
           build_base_payload(chat_messages, model, stream).tap do |payload|
-            add_optional_fields(payload, system_content:, tools:, temperature:)
+            add_optional_fields(payload, system_content:, tools:, tool_prefs:, temperature:)
           end
         end
+        # rubocop:enable Metrics/ParameterLists,Lint/UnusedMethodArgument
 
         def separate_messages(messages)
           messages.partition { |msg| msg.role == :system }
@@ -44,8 +47,12 @@ def build_base_payload(chat_messages, model, stream)
           }
         end
 
-        def add_optional_fields(payload, system_content:, tools:, temperature:)
-          payload[:tools] = tools.values.map { |t| Tools.function_for(t) } if tools.any?
+        def add_optional_fields(payload, system_content:, tools:, tool_prefs:, temperature:)
+          if tools.any?
+            payload[:tools] = tools.values.map { |t| Tools.function_for(t) }
+            payload[:tool_choice] = Tools.build_tool_choice(tool_prefs) unless tool_prefs[:choice].nil?
+          end
+
           payload[:system] = system_content unless system_content.empty?
           payload[:temperature] = temperature unless temperature.nil?
         end
diff --git a/lib/ruby_llm/providers/anthropic/tools.rb b/lib/ruby_llm/providers/anthropic/tools.rb
index 08b9b1725..c8949c6f4 100644
--- a/lib/ruby_llm/providers/anthropic/tools.rb
+++ b/lib/ruby_llm/providers/anthropic/tools.rb
@@ -101,6 +101,25 @@ def clean_parameters(parameters)
         def required_parameters(parameters)
           parameters.select { |_, param| param.required }.keys
         end
+
+        def build_tool_choice(tool_prefs)
+          tool_choice = tool_prefs[:choice]
+          parallel_tool_calls = tool_prefs[:parallel]
+
+          {
+            type: case tool_choice
+                  when :auto, :none
+                    tool_choice
+                  when :required
+                    :any
+                  else
+                    :tool
+                  end
+          }.tap do |tc|
+            tc[:name] = tool_choice if tc[:type] == :tool
+            tc[:disable_parallel_tool_use] = !parallel_tool_calls unless tc[:type] == :none || parallel_tool_calls.nil?
+          end
+        end
       end
     end
   end
diff --git a/lib/ruby_llm/providers/bedrock/capabilities.rb b/lib/ruby_llm/providers/bedrock/capabilities.rb
index 94b8e1438..757f02be2 100644
--- a/lib/ruby_llm/providers/bedrock/capabilities.rb
+++ b/lib/ruby_llm/providers/bedrock/capabilities.rb
@@ -46,6 +46,14 @@ def supports_functions?(model_id)
           model_id.match?(/anthropic\.claude/)
         end
 
+        def supports_tool_choice?(model_id)
+          model_id.match?(/anthropic\.claude/)
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          false
+        end
+
         def supports_audio?(_model_id)
           false
         end
diff --git a/lib/ruby_llm/providers/bedrock/chat.rb b/lib/ruby_llm/providers/bedrock/chat.rb
index 4abdae3f3..c90544e41 100644
--- a/lib/ruby_llm/providers/bedrock/chat.rb
+++ b/lib/ruby_llm/providers/bedrock/chat.rb
@@ -39,16 +39,20 @@ def completion_url
           "model/#{@model_id}/invoke"
         end
 
-        def render_payload(messages, tools:, temperature:, model:, stream: false, schema: nil) # rubocop:disable Lint/UnusedMethodArgument,Metrics/ParameterLists
+        # rubocop:disable Metrics/ParameterLists,Lint/UnusedMethodArgument
+        def render_payload(messages, tools:, tool_prefs:, temperature:, model:, stream: false,
+                           schema: nil)
           @model_id = model.id
 
           system_messages, chat_messages = Anthropic::Chat.separate_messages(messages)
           system_content = Anthropic::Chat.build_system_content(system_messages)
 
           build_base_payload(chat_messages, model).tap do |payload|
-            Anthropic::Chat.add_optional_fields(payload, system_content:, tools:, temperature:)
+            Anthropic::Chat.add_optional_fields(payload, system_content:, tools:, tool_prefs:,
+                                                         temperature:)
           end
         end
+        # rubocop:enable Metrics/ParameterLists,Lint/UnusedMethodArgument
 
         def build_base_payload(chat_messages, model)
           {
diff --git a/lib/ruby_llm/providers/deepseek/capabilities.rb b/lib/ruby_llm/providers/deepseek/capabilities.rb
index 975f0df9a..8a3bad737 100644
--- a/lib/ruby_llm/providers/deepseek/capabilities.rb
+++ b/lib/ruby_llm/providers/deepseek/capabilities.rb
@@ -41,6 +41,14 @@ def supports_functions?(model_id)
           model_id.match?(/deepseek-chat/)
         end
 
+        def supports_tool_choice?(_model_id)
+          true
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          false
+        end
+
         def supports_json_mode?(_model_id)
           false
         end
diff --git a/lib/ruby_llm/providers/gemini/capabilities.rb b/lib/ruby_llm/providers/gemini/capabilities.rb
index 41b046d9e..528ae9e2f 100644
--- a/lib/ruby_llm/providers/gemini/capabilities.rb
+++ b/lib/ruby_llm/providers/gemini/capabilities.rb
@@ -62,6 +62,14 @@ def supports_functions?(model_id)
           model_id.match?(/gemini|pro|flash/)
         end
 
+        def supports_tool_choice?(_model_id)
+          true
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          false
+        end
+
         def supports_json_mode?(model_id)
           if model_id.match?(/text-embedding|embedding-001|aqa|imagen|gemini-2\.0-flash-lite|gemini-2\.5-pro-exp-03-25/)
             return false
diff --git a/lib/ruby_llm/providers/gemini/chat.rb b/lib/ruby_llm/providers/gemini/chat.rb
index c504b08a2..90685949c 100644
--- a/lib/ruby_llm/providers/gemini/chat.rb
+++ b/lib/ruby_llm/providers/gemini/chat.rb
@@ -11,7 +11,8 @@ def completion_url
           "models/#{@model}:generateContent"
         end
 
-        def render_payload(messages, tools:, temperature:, model:, stream: false, schema: nil) # rubocop:disable Metrics/ParameterLists,Lint/UnusedMethodArgument
+        # rubocop:disable Metrics/ParameterLists,Lint/UnusedMethodArgument
+        def render_payload(messages, tools:, tool_prefs:, temperature:, model:, stream: false, schema: nil)
           @model = model.id
           payload = {
             contents: format_messages(messages),
@@ -25,9 +26,15 @@ def render_payload(messages, tools:, temperature:, model:, stream: false, schema
             payload[:generationConfig][:responseSchema] = convert_schema_to_gemini(schema)
           end
 
-          payload[:tools] = format_tools(tools) if tools.any?
+          if tools.any?
+            payload[:tools] = format_tools(tools)
+            # Gemini doesn't support controlling parallel tool calls
+            payload[:toolConfig] = build_tool_config(tool_prefs[:choice]) unless tool_prefs[:choice].nil?
+          end
+
           payload
         end
+        # rubocop:enable Metrics/ParameterLists,Lint/UnusedMethodArgument
 
         private
 
diff --git a/lib/ruby_llm/providers/gemini/tools.rb b/lib/ruby_llm/providers/gemini/tools.rb
index bef6bfa35..9fbc77029 100644
--- a/lib/ruby_llm/providers/gemini/tools.rb
+++ b/lib/ruby_llm/providers/gemini/tools.rb
@@ -71,6 +71,25 @@ def param_type_for_gemini(type)
           else 'STRING'
           end
         end
+
+        def build_tool_config(tool_choice)
+          {
+            functionCallingConfig: {
+              mode: forced_tool_choice?(tool_choice) ? 'any' : tool_choice
+            }.tap do |config|
+              # Use allowedFunctionNames to simulate specific tool choice
+              config[:allowedFunctionNames] = [tool_choice] if specific_tool_choice?(tool_choice)
+            end
+          }
+        end
+
+        def forced_tool_choice?(tool_choice)
+          tool_choice == :required || specific_tool_choice?(tool_choice)
+        end
+
+        def specific_tool_choice?(tool_choice)
+          !%i[auto none required].include?(tool_choice)
+        end
       end
     end
   end
diff --git a/lib/ruby_llm/providers/gpustack.rb b/lib/ruby_llm/providers/gpustack.rb
index fed40ba99..c91d1a06f 100644
--- a/lib/ruby_llm/providers/gpustack.rb
+++ b/lib/ruby_llm/providers/gpustack.rb
@@ -28,6 +28,10 @@ def local?
         def configuration_requirements
           %i[gpustack_api_base]
         end
+
+        def capabilities
+          GPUStack::Capabilities
+        end
       end
     end
   end
diff --git a/lib/ruby_llm/providers/gpustack/capabilities.rb b/lib/ruby_llm/providers/gpustack/capabilities.rb
new file mode 100644
index 000000000..ad6cb4a28
--- /dev/null
+++ b/lib/ruby_llm/providers/gpustack/capabilities.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module RubyLLM
+  module Providers
+    class GPUStack
+      # Determines capabilities for GPUStack models
+      module Capabilities
+        module_function
+
+        def supports_tool_choice?(_model_id)
+          false
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          false
+        end
+      end
+    end
+  end
+end
diff --git a/lib/ruby_llm/providers/mistral/capabilities.rb b/lib/ruby_llm/providers/mistral/capabilities.rb
index 85616a95a..26a21edc7 100644
--- a/lib/ruby_llm/providers/mistral/capabilities.rb
+++ b/lib/ruby_llm/providers/mistral/capabilities.rb
@@ -15,6 +15,14 @@ def supports_tools?(model_id)
           !model_id.match?(/embed|moderation|ocr|voxtral|transcriptions|mistral-(tiny|small)-(2312|2402)/)
         end
 
+        def supports_tool_choice?(_model_id)
+          true
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          true
+        end
+
         def supports_vision?(model_id)
           model_id.match?(/pixtral|mistral-small-(2503|2506)|mistral-medium/)
         end
diff --git a/lib/ruby_llm/providers/mistral/chat.rb b/lib/ruby_llm/providers/mistral/chat.rb
index 10ec965e4..a48eeaadc 100644
--- a/lib/ruby_llm/providers/mistral/chat.rb
+++ b/lib/ruby_llm/providers/mistral/chat.rb
@@ -12,7 +12,8 @@ def format_role(role)
         end
 
         # rubocop:disable Metrics/ParameterLists
-        def render_payload(messages, tools:, temperature:, model:, stream: false, schema: nil)
+        def render_payload(messages, tools:, tool_prefs:, temperature:, model:, stream: false,
+                           schema: nil)
           payload = super
           payload.delete(:stream_options)
           payload
diff --git a/lib/ruby_llm/providers/ollama.rb b/lib/ruby_llm/providers/ollama.rb
index ea20c4953..2c4182291 100644
--- a/lib/ruby_llm/providers/ollama.rb
+++ b/lib/ruby_llm/providers/ollama.rb
@@ -24,6 +24,10 @@ def configuration_requirements
         def local?
           true
         end
+
+        def capabilities
+          Ollama::Capabilities
+        end
       end
     end
   end
diff --git a/lib/ruby_llm/providers/ollama/capabilities.rb b/lib/ruby_llm/providers/ollama/capabilities.rb
new file mode 100644
index 000000000..225181db7
--- /dev/null
+++ b/lib/ruby_llm/providers/ollama/capabilities.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module RubyLLM
+  module Providers
+    class Ollama
+      # Determines capabilities for Ollama models
+      module Capabilities
+        module_function
+
+        def supports_tool_choice?(_model_id)
+          false
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          false
+        end
+      end
+    end
+  end
+end
diff --git a/lib/ruby_llm/providers/openai/capabilities.rb b/lib/ruby_llm/providers/openai/capabilities.rb
index 37c320da8..cbfd57cca 100644
--- a/lib/ruby_llm/providers/openai/capabilities.rb
+++ b/lib/ruby_llm/providers/openai/capabilities.rb
@@ -97,6 +97,14 @@ def supports_functions?(model_id)
           end
         end
 
+        def supports_tool_choice?(_model_id)
+          true
+        end
+
+        def supports_tool_parallel_control?(_model_id)
+          true
+        end
+
         def supports_structured_output?(model_id)
           case model_family(model_id)
           when 'gpt5', 'gpt5_mini', 'gpt5_nano', 'gpt41', 'gpt41_mini', 'gpt41_nano', 'chatgpt4o', 'gpt4o',
diff --git a/lib/ruby_llm/providers/openai/chat.rb b/lib/ruby_llm/providers/openai/chat.rb
index e6d58ec05..c22e85457 100644
--- a/lib/ruby_llm/providers/openai/chat.rb
+++ b/lib/ruby_llm/providers/openai/chat.rb
@@ -11,7 +11,8 @@ def completion_url
 
         module_function
 
-        def render_payload(messages, tools:, temperature:, model:, stream: false, schema: nil) # rubocop:disable Metrics/ParameterLists
+        # rubocop:disable Metrics/ParameterLists
+        def render_payload(messages, tools:, tool_prefs:, temperature:, model:, stream: false, schema: nil)
           payload = {
             model: model.id,
             messages: format_messages(messages),
@@ -19,7 +20,12 @@ def render_payload(messages, tools:, temperature:, model:, stream: false, schema
           }
 
           payload[:temperature] = temperature unless temperature.nil?
-          payload[:tools] = tools.map { |_, tool| tool_for(tool) } if tools.any?
+
+          if tools.any?
+            payload[:tools] = tools.map { |_, tool| tool_for(tool) }
+            payload[:tool_choice] = build_tool_choice(tool_prefs[:choice]) unless tool_prefs[:choice].nil?
+            payload[:parallel_tool_calls] = tool_prefs[:parallel] unless tool_prefs[:parallel].nil?
+          end
 
           if schema
             strict = schema[:strict] != false
@@ -37,6 +43,7 @@ def render_payload(messages, tools:, temperature:, model:, stream: false, schema
           payload[:stream_options] = { include_usage: true } if stream
           payload
         end
+        # rubocop:enable Metrics/ParameterLists
 
         def parse_completion_response(response)
           data = response.body
diff --git a/lib/ruby_llm/providers/openai/tools.rb b/lib/ruby_llm/providers/openai/tools.rb
index 94bb97429..d13752cc3 100644
--- a/lib/ruby_llm/providers/openai/tools.rb
+++ b/lib/ruby_llm/providers/openai/tools.rb
@@ -72,6 +72,20 @@ def parse_tool_calls(tool_calls, parse_arguments: true)
             ]
           end
         end
+
+        def build_tool_choice(tool_choice)
+          case tool_choice
+          when :auto, :none, :required
+            tool_choice
+          else
+            {
+              type: 'function',
+              function: {
+                name: tool_choice
+              }
+            }
+          end
+        end
       end
     end
   end
diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_anthropic_claude-3-5-haiku-20241022_respects_choice_none.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_anthropic_claude-3-5-haiku-20241022_respects_choice_none.yml
new file mode 100644
index 000000000..ea830aab3
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_anthropic_claude-3-5-haiku-20241022_respects_choice_none.yml
@@ -0,0 +1,86 @@
+---
+http_interactions:
+- request:
+    method: post
+    uri: https://api.anthropic.com/v1/messages
+    body:
+      encoding: UTF-8
+      string: '{"model":"claude-3-5-haiku-20241022","messages":[{"role":"user","content":[{"type":"text","text":"What''s
+        the weather in Berlin? (52.5200, 13.4050)"}]}],"stream":false,"max_tokens":8192,"tools":[{"name":"weather","description":"Gets
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+      Date:
+      - Tue, 23 Sep 2025 22:59:36 GMT
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+      - application/json
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+  recorded_at: Tue, 23 Sep 2025 22:59:36 GMT
+- request:
+    method: post
+    uri: https://bedrock-runtime.<AWS_REGION>.amazonaws.com/model/anthropic.claude-3-5-haiku-20241022-v1:0/invoke
+    body:
+      encoding: UTF-8
+      string: '{"anthropic_version":"bedrock-2023-05-31","messages":[{"role":"user","content":[{"type":"text","text":"What''s
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+      message: OK
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+      Date:
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+        the Fall of Rome. Let me provide a historical explanation:\n\nThe Fall of
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+        which occurred gradually over several centuries, traditionally marked by the
+        deposition of the last Roman Emperor Romulus Augustulus in 476 CE by the Germanic
+        king Odoacer.\n\nKey points about the Fall of Rome include:\n\n1. Multiple
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+        challenges:\n- Political instability and frequent civil wars\n- Economic decline
+        and overextension of the empire\n- Military pressures from Germanic tribes
+        and other external invaders\n- Social and moral decay\n- Corruption in government\n-
+        Division of the empire into Western and Eastern (Byzantine) halves\n\n2. Barbarian
+        Invasions: Germanic tribes like the Goths, Vandals, and Franks continuously
+        pressured Roman borders and eventually settled within imperial territories.\n\n3.
+        Economic Challenges: High taxation, decreased agricultural productivity, and
+        reduced trade weakened the empire''s economic foundation.\n\n4. Military Weakness:
+        The Roman military became less effective, relying more on mercenaries and
+        struggling to defend vast territories.\n\n5. Cultural Transformation: Rather
+        than a sudden collapse, it was more a gradual transformation where Roman institutions
+        were replaced by Germanic kingdoms.\n\nThe Eastern Roman Empire (Byzantine
+        Empire) continued to exist for nearly a thousand years more, until Constantinople
+        fell to the Ottoman Turks in 1453."}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":491,"cache_creation_input_tokens":0,"cache_read_input_tokens":0,"output_tokens":331}}'
+  recorded_at: Tue, 23 Sep 2025 22:59:42 GMT
+recorded_with: VCR 6.3.1
diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_choice_none.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_choice_none.yml
new file mode 100644
index 000000000..7111e97d7
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_choice_none.yml
@@ -0,0 +1,60 @@
+---
+http_interactions:
+- request:
+    method: post
+    uri: https://api.deepseek.com/chat/completions
+    body:
+      encoding: UTF-8
+      string: '{"model":"deepseek-chat","messages":[{"role":"user","content":"What''s
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+    headers:
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+      message: OK
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+      Date:
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+  recorded_at: Tue, 23 Sep 2025 21:37:00 GMT
+recorded_with: VCR 6.3.1
diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_choice_required_for_unrelated_queries.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_choice_required_for_unrelated_queries.yml
new file mode 100644
index 000000000..f6ffa2b9d
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_choice_required_for_unrelated_queries.yml
@@ -0,0 +1,118 @@
+---
+http_interactions:
+- request:
+    method: post
+    uri: https://api.deepseek.com/chat/completions
+    body:
+      encoding: UTF-8
+      string: '{"model":"deepseek-chat","messages":[{"role":"user","content":"When
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+  recorded_at: Tue, 23 Sep 2025 21:45:17 GMT
+- request:
+    method: post
+    uri: https://api.deepseek.com/chat/completions
+    body:
+      encoding: UTF-8
+      string: '{"model":"deepseek-chat","messages":[{"role":"user","content":"When
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+  recorded_at: Tue, 23 Sep 2025 21:45:27 GMT
+recorded_with: VCR 6.3.1
diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_specific_tool_choice.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_specific_tool_choice.yml
new file mode 100644
index 000000000..cb8b9cca5
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_deepseek_deepseek-chat_respects_specific_tool_choice.yml
@@ -0,0 +1,118 @@
+---
+http_interactions:
+- request:
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+    uri: https://api.deepseek.com/chat/completions
+    body:
+      encoding: UTF-8
+      string: '{"model":"deepseek-chat","messages":[{"role":"user","content":"What''s
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diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_gemini_gemini-2_5-flash_respects_choice_none.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_gemini_gemini-2_5-flash_respects_choice_none.yml
new file mode 100644
index 000000000..29654ebe9
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_gemini_gemini-2_5-flash_respects_choice_none.yml
@@ -0,0 +1,85 @@
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diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_gemini_gemini-2_5-flash_respects_choice_required_for_unrelated_queries.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_gemini_gemini-2_5-flash_respects_choice_required_for_unrelated_queries.yml
new file mode 100644
index 000000000..840aeb232
--- /dev/null
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@@ -0,0 +1,146 @@
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diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_gemini_gemini-2_5-flash_respects_specific_tool_choice.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_gemini_gemini-2_5-flash_respects_specific_tool_choice.yml
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@@ -0,0 +1,174 @@
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diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_mistral_mistral-small-latest_respects_choice_none.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_mistral_mistral-small-latest_respects_choice_none.yml
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index 000000000..e5950661a
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_mistral_mistral-small-latest_respects_choice_none.yml
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diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_mistral_mistral-small-latest_respects_parallel_false_for_sequential_execution.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_mistral_mistral-small-latest_respects_parallel_false_for_sequential_execution.yml
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+recorded_with: VCR 6.3.1
diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_openrouter_anthropic_claude-3_5-haiku_respects_specific_tool_choice.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_openrouter_anthropic_claude-3_5-haiku_respects_specific_tool_choice.yml
new file mode 100644
index 000000000..d0e485338
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_openrouter_anthropic_claude-3_5-haiku_respects_specific_tool_choice.yml
@@ -0,0 +1,112 @@
+---
+http_interactions:
+- request:
+    method: post
+    uri: https://openrouter.ai/api/v1/chat/completions
+    body:
+      encoding: UTF-8
+      string: '{"model":"anthropic/claude-3.5-haiku","messages":[{"role":"user","content":"What''s
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+      message: OK
+    headers:
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+  recorded_at: Tue, 23 Sep 2025 23:00:07 GMT
+- request:
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+    uri: https://openrouter.ai/api/v1/chat/completions
+    body:
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+    headers:
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+      Accept:
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+  response:
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+      message: OK
+    headers:
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+      Content-Type:
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+  recorded_at: Tue, 23 Sep 2025 23:00:14 GMT
+recorded_with: VCR 6.3.1
diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_choice_none.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_choice_none.yml
new file mode 100644
index 000000000..d94df47c0
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_choice_none.yml
@@ -0,0 +1,111 @@
+---
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+  recorded_at: Tue, 23 Sep 2025 23:40:16 GMT
+- request:
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diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_choice_required_for_unrelated_queries.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_choice_required_for_unrelated_queries.yml
new file mode 100644
index 000000000..6a4510b0b
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_choice_required_for_unrelated_queries.yml
@@ -0,0 +1,302 @@
+---
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diff --git a/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_specific_tool_choice.yml b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_specific_tool_choice.yml
new file mode 100644
index 000000000..713d7e83b
--- /dev/null
+++ b/spec/fixtures/vcr_cassettes/chat_tool_choice_and_parallel_control_vertexai_gemini-2_5-flash_respects_specific_tool_choice.yml
@@ -0,0 +1,300 @@
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diff --git a/spec/ruby_llm/chat_tools_spec.rb b/spec/ruby_llm/chat_tools_spec.rb
index cff534172..483d5a0e1 100644
--- a/spec/ruby_llm/chat_tools_spec.rb
+++ b/spec/ruby_llm/chat_tools_spec.rb
@@ -377,6 +377,108 @@ def execute(query:)
     end
   end
 
+  describe 'tool choice and parallel control' do
+    CHAT_MODELS.each do |model_info|
+      model = model_info[:model]
+      provider = model_info[:provider]
+
+      it "#{provider}/#{model} respects choice: :none" do
+        unless RubyLLM::Provider.providers[provider]&.local?
+          model_info = RubyLLM.models.find(model)
+          skip "#{model} doesn't support function calling" unless model_info&.supports_functions?
+        end
+
+        provider_class = provider ? RubyLLM::Provider.providers[provider.to_sym] : nil
+        skip "#{provider} doesn't support tool choice" unless provider_class&.capabilities&.supports_tool_choice?(model)
+
+        skip "Bedrock doesn't support :none tool choice" if provider == :bedrock
+
+        chat = RubyLLM.chat(model: model, provider: provider)
+                      .with_tool(Weather, choice: :none)
+
+        tool_called = false
+        chat.on_tool_call do |_tool_call|
+          tool_called = true
+        end
+
+        response = chat.ask("What's the weather in Berlin? (52.5200, 13.4050)")
+
+        expect(tool_called).to be(false)
+        expect(response.content).not_to include('15°C') # Should not contain tool result
+      end
+
+      it "#{provider}/#{model} respects choice: :required for unrelated queries" do
+        unless RubyLLM::Provider.providers[provider]&.local?
+          model_info = RubyLLM.models.find(model)
+          skip "#{model} doesn't support function calling" unless model_info&.supports_functions?
+        end
+
+        provider_class = provider ? RubyLLM::Provider.providers[provider.to_sym] : nil
+        skip "#{provider} doesn't support tool choice" unless provider_class&.capabilities&.supports_tool_choice?(model)
+
+        chat = RubyLLM.chat(model: model, provider: provider)
+                      .with_tool(Weather, choice: :required)
+
+        tool_called = false
+        chat.on_tool_call do |_tool_call|
+          tool_called = true
+        end
+
+        # Ask about Roman history - completely unrelated to weather
+        chat.ask('When was the fall of Rome?')
+
+        expect(tool_called).to be(true) # Tool should be forced to run
+      end
+
+      it "#{provider}/#{model} respects specific tool choice" do
+        unless RubyLLM::Provider.providers[provider]&.local?
+          model_info = RubyLLM.models.find(model)
+          skip "#{model} doesn't support function calling" unless model_info&.supports_functions?
+        end
+
+        provider_class = provider ? RubyLLM::Provider.providers[provider.to_sym] : nil
+        skip "#{provider} doesn't support tool choice" unless provider_class&.capabilities&.supports_tool_choice?(model)
+
+        chat = RubyLLM.chat(model: model, provider: provider)
+                      .with_tool(Weather, choice: :weather)
+
+        tool_called = false
+        chat.on_tool_call do |_tool_call|
+          tool_called = true
+        end
+
+        # Ask about Roman history - completely unrelated to weather
+        chat.ask("What's the fall of Rome?")
+
+        expect(tool_called).to be(true)
+      end
+
+      it "#{provider}/#{model} respects parallel: false for sequential execution" do
+        unless RubyLLM::Provider.providers[provider]&.local?
+          model_info = RubyLLM.models.find(model)
+          skip "#{model} doesn't support function calling" unless model_info&.supports_functions?
+        end
+
+        provider_class = provider ? RubyLLM::Provider.providers[provider.to_sym] : nil
+        unless provider_class&.capabilities&.supports_tool_parallel_control?(model)
+          skip "#{provider} doesn't support tool parallel control"
+        end
+
+        chat = RubyLLM.chat(model: model, provider: provider)
+                      .with_tools(Weather, BestLanguageToLearn, parallel: false)
+                      .with_instructions(
+                        'You must use both the weather tool for Berlin (52.5200, 13.4050) and the best language tool.'
+                      )
+
+        chat.on_end_message do |message|
+          expect(message.tool_calls.length).to eq(1) if message.tool_call?
+        end
+
+        chat.ask("What's the weather in Berlin and what's the best programming language?")
+      end
+    end
+  end
+
   describe 'error handling' do
     it 'raises an error when tool execution fails' do
       chat = RubyLLM.chat.with_tool(BrokenTool)