diff --git a/operation/search/search.go b/operation/search/search.go
index 3dee452..83a5d14 100644
--- a/operation/search/search.go
+++ b/operation/search/search.go
@@ -27,7 +27,7 @@ var (
 	SearchUsersTool = mcp.NewTool(
 		SearchUsersToolName,
 		mcp.WithDescription("search users"),
-		mcp.WithString("keyword", mcp.Description("Keyword")),
+		mcp.WithString("keyword", mcp.Required(), mcp.Description("Keyword")),
 		mcp.WithNumber("page", mcp.Description("Page"), mcp.DefaultNumber(1)),
 		mcp.WithNumber("pageSize", mcp.Description("PageSize"), mcp.DefaultNumber(100)),
 	)
@@ -35,8 +35,8 @@ var (
 	SearOrgTeamsTool = mcp.NewTool(
 		SearchOrgTeamsToolName,
 		mcp.WithDescription("search organization teams"),
-		mcp.WithString("org", mcp.Description("organization name")),
-		mcp.WithString("query", mcp.Description("search organization teams")),
+		mcp.WithString("org", mcp.Required(), mcp.Description("organization name")),
+		mcp.WithString("query", mcp.Required(), mcp.Description("search organization teams")),
 		mcp.WithBoolean("includeDescription", mcp.Description("include description?")),
 		mcp.WithNumber("page", mcp.Description("Page"), mcp.DefaultNumber(1)),
 		mcp.WithNumber("pageSize", mcp.Description("PageSize"), mcp.DefaultNumber(100)),
@@ -45,7 +45,7 @@ var (
 	SearchReposTool = mcp.NewTool(
 		SearchReposToolName,
 		mcp.WithDescription("search repos"),
-		mcp.WithString("keyword", mcp.Description("Keyword")),
+		mcp.WithString("keyword", mcp.Required(), mcp.Description("Keyword")),
 		mcp.WithBoolean("keywordIsTopic", mcp.Description("KeywordIsTopic")),
 		mcp.WithBoolean("keywordInDescription", mcp.Description("KeywordInDescription")),
 		mcp.WithNumber("ownerID", mcp.Description("OwnerID")),
diff --git a/operation/search/search_test.go b/operation/search/search_test.go
new file mode 100644
index 0000000..81e37e3
--- /dev/null
+++ b/operation/search/search_test.go
@@ -0,0 +1,42 @@
+package search
+
+import (
+	"slices"
+	"testing"
+
+	"github.com/mark3labs/mcp-go/mcp"
+)
+
+func TestSearchToolsRequiredFields(t *testing.T) {
+	tests := []struct {
+		name     string
+		tool     mcp.Tool
+		required []string
+	}{
+		{
+			name:     "search_users",
+			tool:     SearchUsersTool,
+			required: []string{"keyword"},
+		},
+		{
+			name:     "search_org_teams",
+			tool:     SearOrgTeamsTool,
+			required: []string{"org", "query"},
+		},
+		{
+			name:     "search_repos",
+			tool:     SearchReposTool,
+			required: []string{"keyword"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			for _, field := range tt.required {
+				if !slices.Contains(tt.tool.InputSchema.Required, field) {
+					t.Errorf("tool %s: expected %q to be required, got required=%v", tt.name, field, tt.tool.InputSchema.Required)
+				}
+			}
+		})
+	}
+}