diff --git a/internal/tools/barbican/barbican.go b/internal/tools/barbican/barbican.go
index a09ac96..1cba219 100644
--- a/internal/tools/barbican/barbican.go
+++ b/internal/tools/barbican/barbican.go
@@ -91,6 +91,9 @@ func getSecretHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if secretID == "" {
 			return shared.ToolError("secret_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(secretID, "secret_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		secret, err := secrets.Get(ctx, client, secretID).Extract()
 		if err != nil {
diff --git a/internal/tools/castellum/castellum.go b/internal/tools/castellum/castellum.go
index 0c1f15f..02275ad 100644
--- a/internal/tools/castellum/castellum.go
+++ b/internal/tools/castellum/castellum.go
@@ -11,7 +11,6 @@ import (
 	"errors"
 	"net/http"
 	"net/url"
-	"regexp"
 
 	"github.com/gophercloud/gophercloud/v2"
 	"github.com/mark3labs/mcp-go/mcp"
@@ -49,9 +48,6 @@ var listRecentlyFailedOperationsTool = mcp.NewTool("castellum_list_recently_fail
 	mcp.WithString("max_age", mcp.Description("Time window for results (e.g., '12h', '7d'). Default: '1d'")),
 )
 
-// uuidPattern validates that a string is a proper UUID to prevent path traversal.
-var uuidPattern = regexp.MustCompile(`(?i)^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$`)
-
 func getProjectResourcesHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 	return func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
 		client, err := provider.CastellumClient()
@@ -63,8 +59,8 @@ func getProjectResourcesHandler(provider *auth.Provider) mcpserver.ToolHandlerFu
 		if projectID == "" {
 			return shared.ToolError("project_id is required"), nil
 		}
-		if !uuidPattern.MatchString(projectID) {
-			return shared.ToolError("project_id must be a valid UUID"), nil
+		if errResult := shared.ValidateUUID(projectID, "project_id"); errResult != nil {
+			return errResult, nil
 		}
 
 		reqURL := client.Endpoint + "v1/projects/" + projectID
@@ -161,7 +157,7 @@ func buildOperationsQuery(request mcp.CallToolRequest) (string, error) {
 	params := url.Values{}
 
 	if projectID := shared.StringParam(request, "project_id"); projectID != "" {
-		if !uuidPattern.MatchString(projectID) {
+		if errResult := shared.ValidateUUID(projectID, "project_id"); errResult != nil {
 			return "", errors.New("project_id must be a valid UUID")
 		}
 		params.Set("project", projectID)
diff --git a/internal/tools/cinder/cinder.go b/internal/tools/cinder/cinder.go
index 5375785..6ff264a 100644
--- a/internal/tools/cinder/cinder.go
+++ b/internal/tools/cinder/cinder.go
@@ -94,6 +94,9 @@ func getVolumeHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if volumeID == "" {
 			return shared.ToolError("volume_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(volumeID, "volume_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		vol, err := volumes.Get(ctx, client, volumeID).Extract()
 		if err != nil {
diff --git a/internal/tools/designate/designate.go b/internal/tools/designate/designate.go
index 95710bb..75c57a9 100644
--- a/internal/tools/designate/designate.go
+++ b/internal/tools/designate/designate.go
@@ -105,6 +105,9 @@ func getZoneHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if zoneID == "" {
 			return shared.ToolError("zone_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(zoneID, "zone_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		zone, err := zones.Get(ctx, client, zoneID).Extract()
 		if err != nil {
@@ -130,6 +133,9 @@ func listRecordsetsHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if zoneID == "" {
 			return shared.ToolError("zone_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(zoneID, "zone_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		opts := recordsets.ListOpts{
 			Name:   shared.StringParam(request, "name"),
diff --git a/internal/tools/glance/glance.go b/internal/tools/glance/glance.go
index 56236d0..3632519 100644
--- a/internal/tools/glance/glance.go
+++ b/internal/tools/glance/glance.go
@@ -104,6 +104,9 @@ func getImageHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if imageID == "" {
 			return shared.ToolError("image_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(imageID, "image_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		img, err := images.Get(ctx, client, imageID).Extract()
 		if err != nil {
diff --git a/internal/tools/hermes/hermes.go b/internal/tools/hermes/hermes.go
index 3ac0a97..9db0bf7 100644
--- a/internal/tools/hermes/hermes.go
+++ b/internal/tools/hermes/hermes.go
@@ -9,8 +9,8 @@ import (
 	"context"
 	"encoding/json"
 	"net/http"
+	"net/url"
 	"strconv"
-	"strings"
 
 	"github.com/gophercloud/gophercloud/v2"
 	"github.com/mark3labs/mcp-go/mcp"
@@ -63,45 +63,38 @@ func listEventsHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 			return shared.ToolError("failed to get hermes client: %v", err), nil
 		}
 
-		query := make(map[string]string)
+		params := url.Values{}
 		for _, key := range []string{"target_type", "target_id", "initiator_name", "initiator_id", "action", "outcome", "observer_type", "sort"} {
 			if v := shared.StringParam(request, key); v != "" {
-				query[key] = v
+				params.Set(key, v)
 			}
 		}
 		if v := shared.StringParam(request, "time_gte"); v != "" {
-			query["time"] = "gte:" + v
+			timeFilter := "gte:" + v
 			if lte := shared.StringParam(request, "time_lte"); lte != "" {
-				query["time"] += ",lte:" + lte
+				timeFilter += ",lte:" + lte
 			}
+			params.Set("time", timeFilter)
 		}
 
 		limit := int(shared.NumberParam(request, "limit"))
 		if limit <= 0 {
 			limit = 50
 		}
-		query["limit"] = strconv.Itoa(limit)
+		params.Set("limit", strconv.Itoa(limit))
 
 		if offset := int(shared.NumberParam(request, "offset")); offset > 0 {
-			query["offset"] = strconv.Itoa(offset)
+			params.Set("offset", strconv.Itoa(offset))
 		}
 
-		var buf strings.Builder
-		buf.WriteString(client.ResourceBase)
-		buf.WriteString("events")
-		sep := "?"
-		for k, v := range query {
-			buf.WriteString(sep)
-			buf.WriteString(k)
-			buf.WriteString("=")
-			buf.WriteString(v)
-			sep = "&"
+		reqURL := client.ResourceBase + "events"
+		if encoded := params.Encode(); encoded != "" {
+			reqURL += "?" + encoded
 		}
-		url := buf.String()
 
 		var body any
 		//nolint:bodyclose
-		_, err = client.Get(ctx, url, &body, &gophercloud.RequestOpts{
+		_, err = client.Get(ctx, reqURL, &body, &gophercloud.RequestOpts{
 			OkCodes: []int{http.StatusOK},
 		})
 		if err != nil {
@@ -127,12 +120,15 @@ func getEventHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if eventID == "" {
 			return shared.ToolError("event_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(eventID, "event_id"); errResult != nil {
+			return errResult, nil
+		}
 
-		url := client.ResourceBase + "v1/events/" + eventID
+		reqURL := client.ResourceBase + "v1/events/" + eventID
 
 		var body any
 		//nolint:bodyclose
-		_, err = client.Get(ctx, url, &body, &gophercloud.RequestOpts{
+		_, err = client.Get(ctx, reqURL, &body, &gophercloud.RequestOpts{
 			OkCodes: []int{http.StatusOK},
 		})
 		if err != nil {
@@ -159,11 +155,23 @@ func listAttributesHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 			return shared.ToolError("attribute is required"), nil
 		}
 
-		url := client.ResourceBase + "attributes/" + attr
+		// Allowlist of valid attribute names to prevent path traversal.
+		validAttributes := map[string]bool{
+			"target_type":    true,
+			"action":         true,
+			"outcome":        true,
+			"observer_type":  true,
+			"initiator_type": true,
+		}
+		if !validAttributes[attr] {
+			return shared.ToolError("attribute must be one of: target_type, action, outcome, observer_type, initiator_type (got: %q)", attr), nil
+		}
+
+		reqURL := client.ResourceBase + "attributes/" + attr
 
 		var body any
 		//nolint:bodyclose
-		_, err = client.Get(ctx, url, &body, &gophercloud.RequestOpts{
+		_, err = client.Get(ctx, reqURL, &body, &gophercloud.RequestOpts{
 			OkCodes: []int{http.StatusOK},
 		})
 		if err != nil {
diff --git a/internal/tools/ironic/ironic.go b/internal/tools/ironic/ironic.go
index 9b53552..8e7e828 100644
--- a/internal/tools/ironic/ironic.go
+++ b/internal/tools/ironic/ironic.go
@@ -107,6 +107,9 @@ func getNodeHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if nodeID == "" {
 			return shared.ToolError("node_id is required"), nil
 		}
+		if errResult := shared.ValidatePathSegment(nodeID, "node_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		node, err := nodes.Get(ctx, client, nodeID).Extract()
 		if err != nil {
diff --git a/internal/tools/keystone/keystone.go b/internal/tools/keystone/keystone.go
index 1705c53..9bc824c 100644
--- a/internal/tools/keystone/keystone.go
+++ b/internal/tools/keystone/keystone.go
@@ -307,6 +307,9 @@ func deleteAppCredentialHandler(provider *auth.Provider) mcpserver.ToolHandlerFu
 		if id == "" {
 			return shared.ToolError("id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(id, "id"); errResult != nil {
+			return errResult, nil
+		}
 
 		err = applicationcredentials.Delete(ctx, client, userID, id).ExtractErr()
 		if err != nil {
diff --git a/internal/tools/manila/manila.go b/internal/tools/manila/manila.go
index 98c5c90..7b3fd69 100644
--- a/internal/tools/manila/manila.go
+++ b/internal/tools/manila/manila.go
@@ -103,6 +103,9 @@ func getShareHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if shareID == "" {
 			return shared.ToolError("share_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(shareID, "share_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		share, err := shares.Get(ctx, client, shareID).Extract()
 		if err != nil {
diff --git a/internal/tools/nova/nova.go b/internal/tools/nova/nova.go
index 634f2cb..4dd7a44 100644
--- a/internal/tools/nova/nova.go
+++ b/internal/tools/nova/nova.go
@@ -134,6 +134,9 @@ func getServerHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if serverID == "" {
 			return shared.ToolError("server_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(serverID, "server_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		srv, err := servers.Get(ctx, client, serverID).Extract()
 		if err != nil {
@@ -221,6 +224,9 @@ func serverActionHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if serverID == "" || action == "" {
 			return shared.ToolError("server_id and action are required"), nil
 		}
+		if errResult := shared.ValidateUUID(serverID, "server_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		switch action {
 		case "start":
diff --git a/internal/tools/octavia/octavia.go b/internal/tools/octavia/octavia.go
index 2d9a947..f2454f5 100644
--- a/internal/tools/octavia/octavia.go
+++ b/internal/tools/octavia/octavia.go
@@ -116,6 +116,9 @@ func getLoadbalancerHandler(provider *auth.Provider) mcpserver.ToolHandlerFunc {
 		if lbID == "" {
 			return shared.ToolError("loadbalancer_id is required"), nil
 		}
+		if errResult := shared.ValidateUUID(lbID, "loadbalancer_id"); errResult != nil {
+			return errResult, nil
+		}
 
 		lb, err := loadbalancers.Get(ctx, client, lbID).Extract()
 		if err != nil {
diff --git a/internal/tools/shared/helpers_test.go b/internal/tools/shared/helpers_test.go
index b49c0b0..9d9f8c4 100644
--- a/internal/tools/shared/helpers_test.go
+++ b/internal/tools/shared/helpers_test.go
@@ -119,6 +119,16 @@ func TestSafeQueryParams_EncodesValues(t *testing.T) {
 			params: map[string]string{"name": "my server"},
 			want:   "?name=my+server",
 		},
+		{
+			name:   "multiple params joined",
+			params: map[string]string{"action": "create", "outcome": "success"},
+			want:   "?action=create&outcome=success",
+		},
+		{
+			name:   "path traversal in value encoded",
+			params: map[string]string{"name": "../../etc/passwd"},
+			want:   "?name=..%2F..%2Fetc%2Fpasswd",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {