From 45f99e6590237f490e6ceccd92be0e9bee150646 Mon Sep 17 00:00:00 2001
From: Justin Spahr-Summers <justin@anthropic.com>
Date: Tue, 7 Jan 2025 22:36:20 +0000
Subject: [PATCH] Make `Variables` non-optional with resource template URIs

---
 src/server/index.test.ts | 44 ++++++++++++++++++++++++++++++++++++++++
 src/server/index.ts      | 29 +++++++++++++++-----------
 2 files changed, 61 insertions(+), 12 deletions(-)

diff --git a/src/server/index.test.ts b/src/server/index.test.ts
index f6aee24d..99a60e7f 100644
--- a/src/server/index.test.ts
+++ b/src/server/index.test.ts
@@ -1122,6 +1122,50 @@ describe("Server.resource", () => {
     expect(result.resources[1].uri).toBe("test://resource/2");
   });
 
+  test("should pass template variables to readCallback", async () => {
+    const server = new Server({
+      name: "test server",
+      version: "1.0",
+    });
+    const client = new Client({
+      name: "test client",
+      version: "1.0",
+    });
+
+    server.resource(
+      "test",
+      new UriTemplate("test://resource/{category}/{id}"),
+      async (uri, { category, id }) => ({
+        contents: [
+          {
+            uri: uri.href,
+            text: `Category: ${category}, ID: ${id}`,
+          },
+        ],
+      }),
+    );
+
+    const [clientTransport, serverTransport] =
+      InMemoryTransport.createLinkedPair();
+
+    await Promise.all([
+      client.connect(clientTransport),
+      server.connect(serverTransport),
+    ]);
+
+    const result = await client.request(
+      {
+        method: "resources/read",
+        params: {
+          uri: "test://resource/books/123",
+        },
+      },
+      ReadResourceResultSchema,
+    );
+
+    expect(result.contents[0].text).toBe("Category: books, ID: 123");
+  });
+
   test("should prevent duplicate resource registration", () => {
     const server = new Server({
       name: "test server",
diff --git a/src/server/index.ts b/src/server/index.ts
index 159b382a..a0cc2eda 100644
--- a/src/server/index.ts
+++ b/src/server/index.ts
@@ -78,26 +78,30 @@ const EMPTY_OBJECT_JSON_SCHEMA = {
 
 export type ResourceMetadata = Omit<Resource, "uri" | "name">;
 
-export type ReadResourceCallback = (
-  uri: URL,
-  variables?: Variables,
-) => ReadResourceResult | Promise<ReadResourceResult>;
-
 export type ListResourcesCallback = () =>
   | ListResourcesResult
   | Promise<ListResourcesResult>;
 
+export type ReadResourceCallback = (
+  uri: URL,
+) => ReadResourceResult | Promise<ReadResourceResult>;
+
 type RegisteredResource = {
   name: string;
   metadata?: ResourceMetadata;
   readCallback: ReadResourceCallback;
 };
 
+export type ReadResourceTemplateCallback = (
+  uri: URL,
+  variables: Variables,
+) => ReadResourceResult | Promise<ReadResourceResult>;
+
 type RegisteredResourceTemplate = {
   uriTemplate: UriTemplate;
   metadata?: ResourceMetadata;
   listCallback?: ListResourcesCallback;
-  readCallback: ReadResourceCallback;
+  readCallback: ReadResourceTemplateCallback;
 };
 
 /**
@@ -624,7 +628,7 @@ export class Server<
   resource(
     name: string,
     uriTemplate: UriTemplate,
-    readCallback: ReadResourceCallback,
+    readCallback: ReadResourceTemplateCallback,
   ): void;
 
   /**
@@ -634,7 +638,7 @@ export class Server<
     name: string,
     uriTemplate: UriTemplate,
     metadata: ResourceMetadata,
-    readCallback: ReadResourceCallback,
+    readCallback: ReadResourceTemplateCallback,
   ): void;
 
   /**
@@ -644,7 +648,7 @@ export class Server<
     name: string,
     uriTemplate: UriTemplate,
     listCallback: ListResourcesCallback,
-    readCallback: ReadResourceCallback,
+    readCallback: ReadResourceTemplateCallback,
   ): void;
 
   /**
@@ -655,7 +659,7 @@ export class Server<
     uriTemplate: UriTemplate,
     metadata: ResourceMetadata,
     listCallback: ListResourcesCallback,
-    readCallback: ReadResourceCallback,
+    readCallback: ReadResourceTemplateCallback,
   ): void;
 
   resource(
@@ -673,8 +677,8 @@ export class Server<
       listCallback = rest.shift() as ListResourcesCallback;
     }
 
-    const readCallback = rest[0] as ReadResourceCallback;
     if (typeof uriOrTemplate === "string") {
+      const readCallback = rest[0] as ReadResourceCallback;
       this.registerResource({
         name,
         uri: uriOrTemplate,
@@ -682,6 +686,7 @@ export class Server<
         readCallback,
       });
     } else {
+      const readCallback = rest[0] as ReadResourceTemplateCallback;
       this.registerResourceTemplate({
         name,
         uriTemplate: uriOrTemplate,
@@ -727,7 +732,7 @@ export class Server<
     uriTemplate: UriTemplate;
     metadata?: ResourceMetadata;
     listCallback?: ListResourcesCallback;
-    readCallback: ReadResourceCallback;
+    readCallback: ReadResourceTemplateCallback;
   }): void {
     if (this._registeredResourceTemplates[name]) {
       throw new Error(`Resource template ${name} is already registered`);