diff --git a/crates/agent/src/tools/grep_tool.rs b/crates/agent/src/tools/grep_tool.rs
index 827852524559c7981ed180d406552daef95c47a0..bca716c4d1a72778bc0ccf8c825211e303905d49 100644
--- a/crates/agent/src/tools/grep_tool.rs
+++ b/crates/agent/src/tools/grep_tool.rs
@@ -32,8 +32,21 @@ pub struct GrepToolInput {
     /// Do NOT specify a path here! This will only be matched against the code **content**.
     pub regex: String,
     /// A glob pattern for the paths of files to include in the search.
-    /// Supports standard glob patterns like "**/*.rs" or "src/**/*.ts".
+    /// Supports standard glob patterns like "**/*.rs" or "frontend/src/**/*.ts".
     /// If omitted, all files in the project will be searched.
+    ///
+    /// The glob pattern is matched against the full path including the project root directory.
+    ///
+    /// <example>
+    /// If the project has the following root directories:
+    ///
+    /// - /a/b/backend
+    /// - /c/d/frontend
+    ///
+    /// Use "backend/**/*.rs" to search only Rust files in the backend root directory.
+    /// Use "frontend/src/**/*.ts" to search TypeScript files only in the frontend root directory (sub-directory "src").
+    /// Use "**/*.rs" to search Rust files across all root directories.
+    /// </example>
     pub include_pattern: Option<String>,
     /// Optional starting position for paginated results (0-based).
     /// When not provided, starts from the beginning.