diff --git a/apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts b/apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts
index e085feb2a155d..ceaef41d459f3 100644
--- a/apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts
+++ b/apps/server/src/mcp/toolkits/pullRequests/handlers.test.ts
@@ -191,7 +191,7 @@ const makeHarness = Effect.fn("makePullRequestsToolkitHarness")(function* (
     }),
     Layer.mock(Orchestrator.OrchestratorV2)({
       getThreadShell: (id) =>
-        Effect.succeed(id === THREAD_ID && thread ? v2PullRequestThread(thread) : null),
+        Effect.succeed(id === thread?.id ? v2PullRequestThread(thread) : null),
       dispatch,
     }),
     Layer.succeed(SecureRandom.SecureRandom, testCrypto),
@@ -237,6 +237,21 @@ describe("pull request toolkit handlers", () => {
     }),
   );
 
+  it.effect("points a bare thread uuid at the mcp: thread it belongs to", () =>
+    Effect.gen(function* () {
+      const bareId = ThreadId.make("5d0b4a3e-8c1f-4a52-9d37-2f6c7e1b9a04");
+      const harness = yield* makeHarness({
+        thread: { ...makeThread([]), id: ThreadId.make(`mcp:${bareId}`) },
+      });
+      const error = yield* harness
+        .call("link_pull_request", { threadId: bareId, number: 123 })
+        .pipe(Effect.flip);
+      expect(error.message).toBe(`Thread ${bareId} was not found. Did you mean \`mcp:${bareId}\`?`);
+      expect(error).toMatchObject({ _tag: "OrchestratorMcpFailure", code: "thread_not_found" });
+      expect(yield* Ref.get(harness.commands)).toEqual([]);
+    }),
+  );
+
   it.effect("links by URL with source agent on the token's thread", () =>
     Effect.gen(function* () {
       const harness = yield* makeHarness();
diff --git a/apps/server/src/mcp/toolkits/pullRequests/handlers.ts b/apps/server/src/mcp/toolkits/pullRequests/handlers.ts
index 33ce2a0b84bdb..a703a8f5f39fb 100644
--- a/apps/server/src/mcp/toolkits/pullRequests/handlers.ts
+++ b/apps/server/src/mcp/toolkits/pullRequests/handlers.ts
@@ -27,6 +27,7 @@ import {
 } from "../../../sourceControl/threadPullRequests.ts";
 import * as McpInvocationContext from "../../McpInvocationContext.ts";
 import * as McpToolAccess from "../../McpToolAccess.ts";
+import { threadNotFound } from "../../threadAccess.ts";
 import {
   type ListThreadPullRequestsResult,
   PullRequestLinkFailedError,
@@ -40,7 +41,6 @@ import {
   type PullRequestTargetInput,
   PullRequestWatchFailedError,
   PullRequestWatchFromSubagentError,
-  PullRequestThreadNotFoundError,
   PullRequestThreadRequiredError,
   PullRequestGuideFailedError,
   PullRequestProjectNotFoundError,
@@ -226,7 +226,7 @@ const make = Effect.gen(function* () {
       Effect.mapError((cause) => new Failure({ cause })),
     );
     if (Option.isNone(thread) || thread.value.deletedAt !== null) {
-      return yield* new PullRequestThreadNotFoundError({ threadId });
+      return yield* threadNotFound(engine, threadId, `Thread ${threadId} was not found.`);
     }
     return thread.value;
   });
diff --git a/apps/server/src/mcp/toolkits/pullRequests/tools.ts b/apps/server/src/mcp/toolkits/pullRequests/tools.ts
index 789e9fe125235..e86bf3013bc92 100644
--- a/apps/server/src/mcp/toolkits/pullRequests/tools.ts
+++ b/apps/server/src/mcp/toolkits/pullRequests/tools.ts
@@ -104,15 +104,6 @@ export class PullRequestThreadRequiredError extends Schema.TaggedError<PullReque
   }
 }
 
-export class PullRequestThreadNotFoundError extends Schema.TaggedError<PullRequestThreadNotFoundError>()(
-  "PullRequestThreadNotFoundError",
-  { threadId: Schema.String },
-) {
-  override get message(): string {
-    return `Thread ${this.threadId} was not found.`;
-  }
-}
-
 export class PullRequestLinkFailedError extends Schema.TaggedError<PullRequestLinkFailedError>()(
   "PullRequestLinkFailedError",
   { cause: Schema.Defect() },
@@ -193,7 +184,6 @@ export const PullRequestToolError = Schema.Union([
   PullRequestHostRequiredError,
   PullRequestUrlUnavailableError,
   PullRequestThreadRequiredError,
-  PullRequestThreadNotFoundError,
   PullRequestLinkFailedError,
   PullRequestUnlinkFailedError,
   PullRequestListFailedError,