Support removing tools

docs/guides/tools.md

@@ -133,6 +133,46 @@ puts response.content
 {: .warning }
 Ensure the model you select supports function calling/tools. Check model capabilities using `RubyLLM.models.find('your-model-id').supports_functions?`. Attempting to use `with_tool` on an unsupported model will raise `RubyLLM::UnsupportedFunctionsError`.
 
+## Removing Tools
+
+Each tool definition adds to the input tokens for every request, so it is often a good idea to remove tools that are not needed on a given request. You can remove tools from a `Chat` instance using these methods:
+
+### Remove a Single Tool
+
+Use `without_tool` to remove a specific tool by passing either the tool class or instance:
+
+```ruby
+# Remove by class
+chat.without_tool(Weather)
+
+# Or by instance
+chat.without_tool(weather_tool)
+```
+
+### Remove Multiple Tools
+
+Use `without_tools` to remove multiple tools at once:
+
+```ruby
+chat.without_tools(Weather, AnotherTool, some_tool_instance)
+```
+
+### Clear All Tools
+
+To remove all tools from the chat instance:
+
+```ruby
+chat.clear_tools
+```
+
+All these methods return the `Chat` instance, allowing for method chaining:
+
+```ruby
+chat.clear_tools
+  .with_tool(Weather.new)
+  .ask("What's the weather?")
+```
+
 ## The Tool Execution Flow
 
 When you `ask` a question that the model determines requires a tool:

lib/ruby_llm/chat.rb

@@ -54,8 +54,8 @@ def with_tool(tool)
         raise UnsupportedFunctionsError, "Model #{@model.id} doesn't support function calling"
       end
 
-      tool_instance = tool.is_a?(Class) ? tool.new : tool
-      @tools[tool_instance.name.to_sym] = tool_instance
+      tool_instance = instantiate_tool(tool)
+      @tools[tool_name(tool_instance)] = tool_instance
       self
     end
 
@@ -64,6 +64,22 @@ def with_tools(*tools)
       self
     end
 
+    def without_tool(tool)
+      tool_instance = instantiate_tool(tool)
+      @tools.delete(tool_name(tool_instance))
+      self
+    end
+
+    def without_tools(*tools)
+      tools.each { |tool| without_tool(tool) }
+      self
+    end
+
+    def clear_tools
+      @tools.clear
+      self
+    end
+
     def with_model(model_id, provider: nil, assume_exists: false)
       @model, @provider = Models.resolve(model_id, provider:, assume_exists:, config: @config)
       @connection = @provider.connection
@@ -212,6 +228,14 @@ def execute_tool(tool_call)
       tool.call(args)
     end
 
+    def tool_name(tool)
+      tool.name.to_sym
+    end
+
+    def instantiate_tool(tool)
+      tool.is_a?(Class) ? tool.new : tool
+    end
+
     def instance_variables
       super - %i[@connection @config]
     end