address review comments

Author: findleyr

mcp/tool.go

@@ -103,17 +103,21 @@ func applySchema(data json.RawMessage, resolved *jsonschema.Resolved) (json.RawM
 	return data, nil
 }
 
+// validateToolName checks whether name is a valid tool name, reporting a
+// non-nil error if not.
 func validateToolName(name string) error {
 	if name == "" {
 		return fmt.Errorf("tool name cannot be empty")
 	}
 	if len(name) > 128 {
 		return fmt.Errorf("tool name exceeds maximum length of 128 characters (current: %d)", len(name))
 	}
+	// For consistency with other SDKs, report characters in the order the appear
+	// in the name.
 	var invalidChars []string
 	seen := make(map[rune]bool)
 	for _, r := range name {
-		if !((r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '_' || r == '-' || r == '.') {
+		if !validToolNameRune(r) {
 			if !seen[r] {
 				invalidChars = append(invalidChars, fmt.Sprintf("%q", string(r)))
 				seen[r] = true
@@ -125,3 +129,11 @@ func validateToolName(name string) error {
 	}
 	return nil
 }
+
+// validToolNameRune reports whether r is valid within tool names.
+func validToolNameRune(r rune) bool {
+	return (r >= 'a' && r <= 'z') ||
+		(r >= 'A' && r <= 'Z') ||
+		(r >= '0' && r <= '9') ||
+		r == '_' || r == '-' || r == '.'
+}