fix(logs): enforce documented limit and direction bounds server-side

pkg/logs/tools.go

@@ -3,6 +3,8 @@ package logs
 import (
 	"context"
 	"encoding/json"
+	"fmt"
+	"math"
 	"time"
 
 	"github.com/mark3labs/mcp-go/mcp"
@@ -201,18 +203,16 @@ func listLogs(logRepo *LogRepo) server.ServerTool {
 				llParams.EndTime = &endTimeParam
 			}
 
-			if direction, ok, err := validate.OptionalToolParam[string](request, "direction"); err != nil {
+			if direction, err := parseLogDirection(request); err != nil {
 				return mcp.NewToolResultError(err.Error()), nil
-			} else if ok {
-				directionParam := logsclient.LogDirection(direction)
-				llParams.Direction = &directionParam
+			} else if direction != nil {
+				llParams.Direction = direction
 			}
 
-			if limit, ok, err := validate.OptionalToolParam[float64](request, "limit"); err != nil {
+			if limit, err := parseLogsLimit(request); err != nil {
 				return mcp.NewToolResultError(err.Error()), nil
-			} else if ok {
-				limitInt := int(limit)
-				llParams.Limit = &limitInt
+			} else if limit != nil {
+				llParams.Limit = limit
 			}
 
 			response, err := logRepo.ListLogs(ctx, llParams)
@@ -413,11 +413,10 @@ func listLogLabelValues(logRepo *LogRepo) server.ServerTool {
 				params.EndTime = &endTimeParam
 			}
 
-			if direction, ok, err := validate.OptionalToolParam[string](request, "direction"); err != nil {
+			if direction, err := parseLogDirection(request); err != nil {
 				return mcp.NewToolResultError(err.Error()), nil
-			} else if ok {
-				directionParam := logsclient.LogDirection(direction)
-				params.Direction = &directionParam
+			} else if direction != nil {
+				params.Direction = direction
 			}
 
 			values, err := logRepo.ListLogLabelValues(ctx, params)
@@ -434,3 +433,44 @@ func listLogLabelValues(logRepo *LogRepo) server.ServerTool {
 		},
 	}
 }
+
+// parseLogsLimit enforces the documented list_logs limit bounds (1-100,
+// whole numbers). The schema advertises Min(1)/Max(100), but MCP clients can
+// send anything; forwarding out-of-range values only fails downstream as an
+// opaque API error. Returns nil when the parameter is absent (API default).
+func parseLogsLimit(request mcp.CallToolRequest) (*int, error) {
+	limit, ok, err := validate.OptionalToolParam[float64](request, "limit")
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, nil
+	}
+	if math.Trunc(limit) != limit {
+		return nil, fmt.Errorf("invalid limit %v: must be a whole number between 1 and 100", limit)
+	}
+	limitInt := int(limit)
+	if limitInt < 1 || limitInt > 100 {
+		return nil, fmt.Errorf("invalid limit %d: must be between 1 and 100", limitInt)
+	}
+	return &limitInt, nil
+}
+
+// parseLogDirection validates the direction parameter against the
+// backward/forward values the logs API accepts. Returns nil when absent.
+func parseLogDirection(request mcp.CallToolRequest) (*logsclient.LogDirection, error) {
+	direction, ok, err := validate.OptionalToolParam[string](request, "direction")
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, nil
+	}
+	switch logsclient.LogDirection(direction) {
+	case logsclient.Backward, logsclient.Forward:
+		directionParam := logsclient.LogDirection(direction)
+		return &directionParam, nil
+	default:
+		return nil, fmt.Errorf("invalid direction %q: must be one of: backward, forward", direction)
+	}
+}

pkg/logs/tools_test.go

@@ -0,0 +1,54 @@
+package logs
+
+import (
+	"testing"
+
+	"github.com/mark3labs/mcp-go/mcp"
+	logsclient "github.com/render-oss/render-mcp-server/pkg/client/logs"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func toolRequest(args map[string]any) mcp.CallToolRequest {
+	request := mcp.CallToolRequest{}
+	request.Params.Arguments = args
+	return request
+}
+
+func TestParseLogsLimit(t *testing.T) {
+	limit, err := parseLogsLimit(toolRequest(nil))
+	require.NoError(t, err)
+	assert.Nil(t, limit)
+
+	for _, v := range []float64{1, 50, 100} {
+		limit, err := parseLogsLimit(toolRequest(map[string]any{"limit": v}))
+		require.NoError(t, err, "limit %v", v)
+		require.NotNil(t, limit)
+		assert.Equal(t, int(v), *limit)
+	}
+
+	for _, v := range []float64{0, -5, 101, 1000, 2.5} {
+		_, err := parseLogsLimit(toolRequest(map[string]any{"limit": v}))
+		require.Error(t, err, "limit %v", v)
+		assert.Contains(t, err.Error(), "invalid limit")
+	}
+}
+
+func TestParseLogDirection(t *testing.T) {
+	direction, err := parseLogDirection(toolRequest(nil))
+	require.NoError(t, err)
+	assert.Nil(t, direction)
+
+	for _, v := range []string{"backward", "forward"} {
+		direction, err := parseLogDirection(toolRequest(map[string]any{"direction": v}))
+		require.NoError(t, err, "direction %q", v)
+		require.NotNil(t, direction)
+		assert.Equal(t, logsclient.LogDirection(v), *direction)
+	}
+
+	for _, v := range []string{"sideways", "", "BACKWARD"} {
+		_, err := parseLogDirection(toolRequest(map[string]any{"direction": v}))
+		require.Error(t, err, "direction %q", v)
+		assert.Contains(t, err.Error(), "invalid direction")
+	}
+}