diff --git a/packages/server/src/server/agent/agent-manager.test.ts b/packages/server/src/server/agent/agent-manager.test.ts
index da3f9bb2c2..fe38bd92c0 100644
--- a/packages/server/src/server/agent/agent-manager.test.ts
+++ b/packages/server/src/server/agent/agent-manager.test.ts
@@ -3850,15 +3850,12 @@ test.each([
       clients: {
         [provider]: client,
       },
-      providerDefinitions:
-        provider === "pi"
-          ? {
-              pi: {
-                enabled: true,
-                applyToolPolicy: buildProviderRegistry(logger).pi.applyToolPolicy,
-              },
-            }
-          : undefined,
+      providerDefinitions: {
+        [provider]: {
+          enabled: true,
+          applyToolPolicy: buildProviderRegistry(logger)[provider]!.applyToolPolicy,
+        },
+      },
       registry: storage,
       logger,
       mcpBaseUrl: "http://127.0.0.1:6767/mcp/agents",
@@ -3898,8 +3895,12 @@ test.each([
     expect(manager.getAgent(snapshot.id)?.config.mcpServerRequirements).toEqual({
       paseo: "optional",
     });
-    expect(snapshot.config.toolPolicy).toBeUndefined();
-    expect(client.lastConfig?.toolPolicy).toBeUndefined();
+    const expectedPolicy =
+      provider === "codex"
+        ? { preapproved: [{ kind: "mcp", server: "paseo", tool: "finish_execution" }] }
+        : undefined;
+    expect(snapshot.config.toolPolicy).toEqual(expectedPolicy);
+    expect(client.lastConfig?.toolPolicy).toEqual(expectedPolicy);
     expect(client.lastConfig?.mcpServers).toEqual(snapshot.config.mcpServers);
   },
 );
@@ -12608,3 +12609,21 @@ test("an out-of-band command racing idle cleanup waits for the resumed runtime",
   expect(h.commands).toEqual(["/maintenance"]);
   expect(h.prompts).toEqual([]);
 });
+
+test("MCP requirements cannot mark a later plugin server optional", async () => {
+  const workdir = mkdtempSync(join(tmpdir(), "agent-manager-test-"));
+  const manager = new AgentManager({
+    clients: { codex: new TestAgentClient() },
+    registry: new AgentStorage(join(workdir, "agents"), logger),
+    logger,
+  });
+  await expect(
+    manager.createAgent(
+      { provider: "codex", cwd: workdir, mcpServerRequirements: { plugin: "optional" } },
+      undefined,
+      { workspaceId: undefined },
+    ),
+  ).rejects.toThrow(
+    "MCP server requirement 'plugin' requires MCP server 'plugin' in the same agent request",
+  );
+});
diff --git a/packages/server/src/server/agent/agent-manager.ts b/packages/server/src/server/agent/agent-manager.ts
index a0a1246c6a..edfbcc8f21 100644
--- a/packages/server/src/server/agent/agent-manager.ts
+++ b/packages/server/src/server/agent/agent-manager.ts
@@ -5465,10 +5465,8 @@ export class AgentManager {
   private applyProviderConfiguration(config: AgentSessionConfig): AgentSessionConfig {
     const definition = this.providerDefinitions.get(config.provider);
     this.validateToolPolicyServers(config);
+    this.validateMcpServerRequirements(config);
     if (config.toolPolicy && !definition?.applyToolPolicy) {
-      if (config.toolPolicy.enforcement === "if-supported") {
-        return { ...config, toolPolicy: undefined };
-      }
       throw new Error(
         `Provider '${config.provider}' cannot preapprove exact MCP tools for unattended execution`,
       );
@@ -5478,6 +5476,16 @@ export class AgentManager {
       : config;
   }
 
+  private validateMcpServerRequirements(config: AgentSessionConfig): void {
+    for (const name of Object.keys(config.mcpServerRequirements ?? {})) {
+      if (!Object.hasOwn(config.mcpServers ?? {}, name)) {
+        throw new Error(
+          `MCP server requirement '${name}' requires MCP server '${name}' in the same agent request`,
+        );
+      }
+    }
+  }
+
   private validateToolPolicyServers(config: AgentSessionConfig): void {
     if (!config.toolPolicy) return;
     const serverNames = new Set(Object.keys(config.mcpServers ?? {}));
diff --git a/packages/server/src/server/agent/runtime-mcp-config.test.ts b/packages/server/src/server/agent/runtime-mcp-config.test.ts
index 4704d131bb..c740e301c8 100644
--- a/packages/server/src/server/agent/runtime-mcp-config.test.ts
+++ b/packages/server/src/server/agent/runtime-mcp-config.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, test } from "vitest";
 
 import type { AgentSessionConfig } from "./agent-sdk-types.js";
-import { withRuntimePaseoMcpServer } from "./runtime-mcp-config.js";
+import { stripInternalPaseoMcpServer, withRuntimePaseoMcpServer } from "./runtime-mcp-config.js";
 
 const BASE_CONFIG: AgentSessionConfig = {
   provider: "claude",
@@ -49,3 +49,15 @@ describe("withRuntimePaseoMcpServer", () => {
     expect(result.mcpServers).toBeUndefined();
   });
 });
+
+test("stripping an internal MCP server also strips its launch requirement", () => {
+  const result = stripInternalPaseoMcpServer({
+    ...BASE_CONFIG,
+    mcpServerRequirements: { paseo: "optional", hub: "optional" },
+    mcpServers: {
+      paseo: { type: "http", url: "http://127.0.0.1/mcp/agents?callerAgentId=agent-1" },
+      hub: { type: "http", url: "https://hub.test/mcp" },
+    },
+  });
+  expect(result.mcpServerRequirements).toEqual({ hub: "optional" });
+});
diff --git a/packages/server/src/server/agent/runtime-mcp-config.ts b/packages/server/src/server/agent/runtime-mcp-config.ts
index 711638ce2f..0573efcdcf 100644
--- a/packages/server/src/server/agent/runtime-mcp-config.ts
+++ b/packages/server/src/server/agent/runtime-mcp-config.ts
@@ -18,6 +18,11 @@ export function stripInternalPaseoMcpServer(config: AgentSessionConfig): AgentSe
   delete nextMcpServers[PASEO_MCP_SERVER_NAME];
 
   const next = { ...config };
+  if (next.mcpServerRequirements?.[PASEO_MCP_SERVER_NAME]) {
+    next.mcpServerRequirements = { ...next.mcpServerRequirements };
+    delete next.mcpServerRequirements[PASEO_MCP_SERVER_NAME];
+    if (Object.keys(next.mcpServerRequirements).length === 0) delete next.mcpServerRequirements;
+  }
   if (Object.keys(nextMcpServers).length > 0) {
     next.mcpServers = nextMcpServers;
   } else {