diff --git a/test/e2e/images/images.go b/test/e2e/images/images.go
index d1dd46e2ec..0f2e9a2f7e 100644
--- a/test/e2e/images/images.go
+++ b/test/e2e/images/images.go
@@ -117,6 +117,33 @@ const (
 	// Provides ~64 PagerDuty incident management tools (incidents, services, schedules, etc.).
 	PagerDutyMCPServerImage = pagerdutyMCPServerImageURL + ":" + pagerdutyMCPServerImageTag
 
+	timeMCPServerImageURL = "ghcr.io/stacklok/dockyard/uvx/mcp-server-time"
+	timeMCPServerImageTag = "2026.7.10"
+	// timeMCPServerImageDigest pins the 2026-07-27 build of tag 2026.7.10.
+	//
+	// Same failure mode as idaProMCPServerImageDigest above, different symptom:
+	// the tag is mutable, dockyard rebuilds it and resolves Python dependencies
+	// fresh, and the 2026-07-31 rebuild picked up the mcp Python SDK 2.0.0
+	// released 2026-07-28. mcp-server-time imports McpError from
+	// mcp.shared.exceptions, which 2.x moved, so the container now exits on
+	// startup with "ImportError: cannot import name 'McpError' from
+	// 'mcp.shared.exceptions'". The proxy suites then fail with
+	// "timeout waiting for MCP server to be ready".
+	//
+	// Pin the last build that resolved a 1.x mcp until upstream caps the
+	// constraint or adopts the 2.x API. Verified by driving both builds over
+	// stdio: the pinned digest answers initialize, tag 2026.7.10 does not.
+	timeMCPServerImageDigest = "sha256:5cca77dec3fefbacad35e3008ab1660f8725ef246213afb24231504fc73c999d"
+	// TimeMCPServerImage is the stdio backend used by the proxy e2e suites
+	// (proxy_stdio_test.go, stdio_proxy_over_streamable_http_mcp_server_test.go).
+	// Provides get_current_time / convert_time.
+	//
+	// These suites reference this constant rather than the "time" registry entry
+	// so a mutable upstream tag cannot break CI: the registry resolves "time" to
+	// the moving :2026.7.10 tag, which is currently broken. Registry-name
+	// resolution itself is still covered by the suites that run "osv".
+	TimeMCPServerImage = timeMCPServerImageURL + ":" + timeMCPServerImageTag + "@" + timeMCPServerImageDigest
+
 	redisImageURL = "redis"
 	redisImageTag = "7-alpine"
 	// RedisImage is used for Redis-backed session storage in scaling tests.
diff --git a/test/e2e/proxy_stdio_test.go b/test/e2e/proxy_stdio_test.go
index 3e7522d71d..cd281e0b0f 100644
--- a/test/e2e/proxy_stdio_test.go
+++ b/test/e2e/proxy_stdio_test.go
@@ -17,6 +17,7 @@ import (
 
 	"github.com/stacklok/toolhive/pkg/transport/types"
 	"github.com/stacklok/toolhive/test/e2e"
+	"github.com/stacklok/toolhive/test/e2e/images"
 )
 
 const (
@@ -183,7 +184,7 @@ var _ = Describe("Proxy Stdio E2E", Label("proxy", "stdio", "e2e"), Serial, func
 		BeforeEach(func() {
 			transportType = types.TransportTypeStdio
 			proxyMode = "sse"
-			mcpServerName = "time"
+			mcpServerName = images.TimeMCPServerImage
 		})
 		It("should proxy MCP requests successfully", func() {
 			By("Getting time server URL")
@@ -234,7 +235,7 @@ var _ = Describe("Proxy Stdio E2E", Label("proxy", "stdio", "e2e"), Serial, func
 		BeforeEach(func() {
 			transportType = types.TransportTypeStdio
 			proxyMode = "streamable-http"
-			mcpServerName = "time"
+			mcpServerName = images.TimeMCPServerImage
 		})
 		It("should proxy MCP requests successfully", func() {
 			By("Getting time server URL")
diff --git a/test/e2e/stdio_proxy_over_streamable_http_mcp_server_test.go b/test/e2e/stdio_proxy_over_streamable_http_mcp_server_test.go
index 88a4a28309..a1c9c610c0 100644
--- a/test/e2e/stdio_proxy_over_streamable_http_mcp_server_test.go
+++ b/test/e2e/stdio_proxy_over_streamable_http_mcp_server_test.go
@@ -15,6 +15,7 @@ import (
 	. "github.com/onsi/gomega"
 
 	"github.com/stacklok/toolhive/test/e2e"
+	"github.com/stacklok/toolhive/test/e2e/images"
 )
 
 var _ = Describe("TimeStreamableHttpMcpServer", Label("proxy", "streamable-http", "e2e"), Serial, func() {
@@ -44,8 +45,9 @@ var _ = Describe("TimeStreamableHttpMcpServer", Label("proxy", "streamable-http"
 			By("Starting the time MCP server with streamable-http proxy")
 			e2e.NewTHVCommand(config, "run",
 				"--name", serverName,
+				"--transport", "stdio",
 				"--proxy-mode", "streamable-http",
-				"time").ExpectSuccess()
+				images.TimeMCPServerImage).ExpectSuccess()
 
 			By("Waiting for the server to be running")
 			err := e2e.WaitForMCPServer(config, serverName, 60*time.Second)