Wire up find_path tool in agent2 (#35799)

Release Notes:

- N/A

---------

Co-authored-by: Antonio Scandurra <me@as-cii.com>

crates/agent2/src/tools/thinking_tool.rs

@@ -0,0 +1,48 @@
+use agent_client_protocol as acp;
+use anyhow::Result;
+use gpui::{App, SharedString, Task};
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+use std::sync::Arc;
+
+use crate::{AgentTool, ToolCallEventStream};
+
+/// A tool for thinking through problems, brainstorming ideas, or planning without executing any actions.
+/// Use this tool when you need to work through complex problems, develop strategies, or outline approaches before taking action.
+#[derive(Debug, Serialize, Deserialize, JsonSchema)]
+pub struct ThinkingToolInput {
+    /// Content to think about. This should be a description of what to think about or
+    /// a problem to solve.
+    content: String,
+}
+
+pub struct ThinkingTool;
+
+impl AgentTool for ThinkingTool {
+    type Input = ThinkingToolInput;
+
+    fn name(&self) -> SharedString {
+        "thinking".into()
+    }
+
+    fn kind(&self) -> acp::ToolKind {
+        acp::ToolKind::Think
+    }
+
+    fn initial_title(&self, _input: Self::Input) -> SharedString {
+        "Thinking".into()
+    }
+
+    fn run(
+        self: Arc<Self>,
+        input: Self::Input,
+        event_stream: ToolCallEventStream,
+        _cx: &mut App,
+    ) -> Task<Result<String>> {
+        event_stream.send_update(acp::ToolCallUpdateFields {
+            content: Some(vec![input.content.into()]),
+            ..Default::default()
+        });
+        Task::ready(Ok("Finished thinking.".to_string()))
+    }
+}