feat(tools): Add think tool with option to disable it.

crates/q_cli/src/cli/chat/mod.rs

@@ -3071,7 +3071,14 @@ fn create_stream(model_responses: serde_json::Value) -> StreamingClient {
 
 /// Returns all tools supported by Q chat.
 pub fn load_tools() -> Result<HashMap<String, ToolSpec>> {
-    Ok(serde_json::from_str(include_str!("tools/tool_index.json"))?)
+    let mut tools: HashMap<String, ToolSpec> = serde_json::from_str(include_str!("tools/tool_index.json"))?;
+
+    // Only include the think tool if the feature is enabled
+    if !tools::think::Think::should_include_in_tools() {
+        tools.remove("think");
+    }
+
+    Ok(tools)
 }
 
 #[cfg(test)]

crates/q_cli/src/cli/chat/tools/mod.rs

@@ -2,8 +2,8 @@ pub mod execute_bash;
 pub mod fs_read;
 pub mod fs_write;
 pub mod gh_issue;
+pub mod think;
 pub mod use_aws;
-
 use std::collections::HashMap;
 use std::io::Write;
 use std::path::{
@@ -24,6 +24,7 @@ use fs_read::FsRead;
 use fs_write::FsWrite;
 use gh_issue::GhIssue;
 use serde::Deserialize;
+use think::Think;
 use use_aws::UseAws;
 
 use super::consts::MAX_TOOL_RESPONSE_SIZE;
@@ -41,6 +42,7 @@ pub enum Tool {
     ExecuteBash(ExecuteBash),
     UseAws(UseAws),
     GhIssue(GhIssue),
+    Think(Think),
 }
 
 impl Tool {
@@ -52,6 +54,7 @@ impl Tool {
             Tool::ExecuteBash(_) => "execute_bash",
             Tool::UseAws(_) => "use_aws",
             Tool::GhIssue(_) => "gh_issue",
+            Tool::Think(_) => "model_think_tool",
         }
     }
 
@@ -63,6 +66,7 @@ impl Tool {
             Tool::ExecuteBash(execute_bash) => execute_bash.requires_acceptance(),
             Tool::UseAws(use_aws) => use_aws.requires_acceptance(),
             Tool::GhIssue(_) => false,
+            Tool::Think(_) => false,
         }
     }
 
@@ -74,6 +78,7 @@ impl Tool {
             Tool::ExecuteBash(execute_bash) => execute_bash.invoke(updates).await,
             Tool::UseAws(use_aws) => use_aws.invoke(context, updates).await,
             Tool::GhIssue(gh_issue) => gh_issue.invoke(updates).await,
+            Tool::Think(think) => think.invoke(updates).await,
         }
     }
 
@@ -85,6 +90,7 @@ impl Tool {
             Tool::ExecuteBash(execute_bash) => execute_bash.queue_description(updates),
             Tool::UseAws(use_aws) => use_aws.queue_description(updates),
             Tool::GhIssue(gh_issue) => gh_issue.queue_description(updates),
+            Tool::Think(think) => Think::queue_description(think, updates),
         }
     }
 
@@ -96,6 +102,7 @@ impl Tool {
             Tool::ExecuteBash(execute_bash) => execute_bash.validate(ctx).await,
             Tool::UseAws(use_aws) => use_aws.validate(ctx).await,
             Tool::GhIssue(gh_issue) => gh_issue.validate(ctx).await,
+            Tool::Think(think) => think.validate(ctx).await,
         }
     }
 }
@@ -118,6 +125,7 @@ impl TryFrom<AssistantToolUse> for Tool {
             "execute_bash" => Self::ExecuteBash(serde_json::from_value::<ExecuteBash>(value.args).map_err(map_err)?),
             "use_aws" => Self::UseAws(serde_json::from_value::<UseAws>(value.args).map_err(map_err)?),
             "report_issue" => Self::GhIssue(serde_json::from_value::<GhIssue>(value.args).map_err(map_err)?),
+            "think" => Self::Think(serde_json::from_value::<Think>(value.args).map_err(map_err)?),
             unknown => {
                 return Err(ToolUseResult {
                     tool_use_id: value.id,

crates/q_cli/src/cli/chat/tools/think.rs

@@ -0,0 +1,86 @@
+use std::io::Write;
+
+use crossterm::queue;
+use crossterm::style::{
+    self,
+    Color,
+};
+use eyre::Result;
+use fig_settings::settings;
+use serde::Deserialize;
+
+use super::{
+    InvokeOutput,
+    OutputKind,
+};
+
+/// The Think tool allows the model to reason through complex problems during response generation.
+/// It provides a dedicated space for the model to process information from tool call results,
+/// navigate complex decision trees, and improve the quality of responses in multi-step scenarios.
+///
+/// This is a beta feature that can be enabled/disabled via settings:
+/// `q settings enable_thinking true`
+#[derive(Debug, Clone, Deserialize)]
+pub struct Think {
+    /// The thought content that the model wants to process
+    pub thought: String,
+}
+
+impl Think {
+    /// Checks if the thinking feature is enabled in settings
+    fn is_enabled() -> bool {
+        // Default to enabled if setting doesn't exist or can't be read
+        settings::get_value("chat.enableThinking")
+            .map(|val| val.and_then(|v| v.as_bool()).unwrap_or(true))
+            .unwrap_or(true)
+    }
+
+    /// Checks if the think tool should be included in the tool list
+    /// This allows us to completely exclude the tool when the feature is disabled
+    pub fn should_include_in_tools() -> bool {
+        Self::is_enabled()
+    }
+
+    /// Queues up a description of the think tool for the user
+    pub fn queue_description(think: &Think, updates: &mut impl Write) -> Result<()> {
+        // Only show a description if the feature is enabled and there's actual thought content
+        if Self::is_enabled() && !think.thought.trim().is_empty() {
+            // Show a preview of the thought that will be displayed
+            queue!(
+                updates,
+                style::SetForegroundColor(Color::Blue),
+                style::Print("I'll share my reasoning process: "),
+                style::SetForegroundColor(Color::Reset),
+                style::Print(&think.thought),
+                style::Print("\n")
+            )?;
+        }
+        Ok(())
+    }
+
+    /// Invokes the think tool. This doesn't actually perform any system operations,
+    /// it's purely for the model's internal reasoning process.
+    pub async fn invoke(&self, _updates: &mut impl Write) -> Result<InvokeOutput> {
+        // Only process non-empty thoughts if the feature is enabled
+        if Self::is_enabled() && !self.thought.trim().is_empty() {
+            // We've already shown the thought in queue_description
+            // Just return an empty output to avoid duplication
+            return Ok(InvokeOutput {
+                output: OutputKind::Text(String::new()),
+            });
+        }
+
+        // If disabled or empty thought, return empty output
+        Ok(InvokeOutput {
+            output: OutputKind::Text(String::new()),
+        })
+    }
+
+    /// Validates the thought - accepts empty thoughts
+    /// Also checks if the thinking feature is enabled in settings
+    pub async fn validate(&mut self, _ctx: &fig_os_shim::Context) -> Result<()> {
+        // We accept empty thoughts - they'll just be ignored
+        // This makes the tool more robust and prevents errors from blocking the model
+        Ok(())
+    }
+}

crates/q_cli/src/cli/chat/tools/tool_index.json

@@ -172,5 +172,19 @@
       },
       "required": ["title"]
     }
+  },
+  "think":{
+    "name": "think",
+    "description": "The Think Tool is an internal reasoning mechanism enabling the model to systematically approach complex tasks by logically breaking them down before responding or acting; use it specifically for multi-step problems requiring step-by-step dependencies, reasoning through multiple constraints, synthesizing results from previous tool calls, planning intricate sequences of actions, troubleshooting complex errors, or making decisions involving multiple trade-offs. Avoid using it for straightforward tasks, basic information retrieval, summaries, always clearly define the reasoning challenge, structure thoughts explicitly, consider multiple perspectives, and summarize key insights before important decisions or complex tool interactions.",
+    "input_schema": {
+      "type": "object",
+      "properties": {
+        "thought": {
+          "type": "string",
+          "description": "A reflective note or intermediate reasoning step."
+        }
+      },
+      "required": ["thought"]
+    }
   }
 }

crates/q_cli/src/cli/settings.rs

@@ -106,6 +106,7 @@ impl SettingsArgs {
 
                 Ok(ExitCode::SUCCESS)
             },
+
             None => match &self.key {
                 Some(key) => match (&self.value, self.delete) {
                     (None, false) => match fig_settings::settings::get_value(key)? {