From 28da1711c143ccf2a55cfc42f64bd24fbc341296 Mon Sep 17 00:00:00 2001
From: "sentry-junior[bot]"
 <264270552+sentry-junior[bot]@users.noreply.github.com>
Date: Fri, 30 Oct 2026 23:35:34 +0000
Subject: [PATCH] perf(mcp): Load the server stack only when the stdio server
 starts

runMcpServer() imported mcp-core's server and tools, the AI SDK
providers, @sentry/node, and the stdio transport at module load, so
--help, --version, and argument errors paid for all of them. Import
them after the config and token are resolved instead, and load the
auth command and device-code flow only on the paths that use them.

Part of #1761

Co-Authored-By: BYK <burak.kaya@sentry.io>
---
 packages/mcp-server/src/index.ts | 39 +++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/packages/mcp-server/src/index.ts b/packages/mcp-server/src/index.ts
index cd8a1d608..db7d1959d 100644
--- a/packages/mcp-server/src/index.ts
+++ b/packages/mcp-server/src/index.ts
@@ -22,25 +22,16 @@
 
 import { pathToFileURL } from "node:url";
 
-import {
-  getAgentProvider,
-  getResolvedProviderType,
-  setAgentProvider,
-  setProviderBaseUrls,
-} from "@sentry/mcp-core/internal/agents/provider-factory";
-import { buildServer } from "@sentry/mcp-core/server";
+// Keep static imports light: `--help`, `--version`, and argument errors must
+// not load the tools, the AI SDK, or the Sentry SDK. The server stack is
+// imported in runMcpServer() once the server is about to start.
 import { SKILLS } from "@sentry/mcp-core/skills";
-import { sentryBeforeSend } from "@sentry/mcp-core/telem/sentry";
 import { LIB_VERSION } from "@sentry/mcp-core/version";
-import * as Sentry from "@sentry/node";
-import { resolveAccessToken } from "./auth/resolve-token";
-import { authCommand } from "./cli/commands/auth";
 import { printCliLine } from "./cli/output";
 import { merge, parseArgv, parseEnv } from "./cli/parse";
 import { finalize } from "./cli/resolve";
 import type { PartiallyResolvedConfig } from "./cli/types";
 import { buildUsage } from "./cli/usage";
-import { startStdio } from "./transports/stdio";
 
 const defaultPackageName = "@sentry/mcp-server";
 const allSkills = Object.keys(SKILLS) as ReadonlyArray<
@@ -95,6 +86,7 @@ export async function runMcpServer(
         new Error("Use `sentry auth` to manage credentials for `sentry mcp`."),
       );
     }
+    const { authCommand } = await import("./cli/commands/auth");
     await authCommand(rawArgs.slice(1));
     return;
   }
@@ -130,11 +122,32 @@ export async function runMcpServer(
           ...partialCfg,
           accessToken,
         }))
-      : resolveAccessToken(partialCfg)
+      : import("./auth/resolve-token").then(({ resolveAccessToken }) =>
+          resolveAccessToken(partialCfg),
+        )
   ).catch((err) => {
     die(err);
   });
 
+  const [
+    {
+      getAgentProvider,
+      getResolvedProviderType,
+      setAgentProvider,
+      setProviderBaseUrls,
+    },
+    { buildServer },
+    { sentryBeforeSend },
+    Sentry,
+    { startStdio },
+  ] = await Promise.all([
+    import("@sentry/mcp-core/internal/agents/provider-factory"),
+    import("@sentry/mcp-core/server"),
+    import("@sentry/mcp-core/telem/sentry"),
+    import("@sentry/node"),
+    import("./transports/stdio"),
+  ]);
+
   // Configure embedded agent provider
   if (cfg.agentProvider) {
     setAgentProvider(cfg.agentProvider);