feat(client): minimal response-cache substrate (ResponseCacheStore + aggregate-then-write list*())

.changeset/client-response-cache-substrate.md

@@ -0,0 +1,5 @@
+---
+'@modelcontextprotocol/client': major
+---
+
+`Client.listTools()` / `listPrompts()` / `listResources()` / `listResourceTemplates()` now **auto-aggregate every page** when called without a `cursor` and return the complete result with `nextCursor: undefined` (matching the C#, Java, and mcp.d SDKs). Pass an explicit `{ cursor }` string to fetch a single page; the per-page path is unchanged. Existing manual pagination loops keep working — the first iteration returns everything and the loop exits — but can be deleted. The aggregated result is written to the new pluggable `ResponseCacheStore` (default: a fresh per-instance `InMemoryResponseCacheStore`); a `ClientResponseCache` collaborator owns the eviction-generation guard and the derived `tools/list` index that `callTool`'s output validation and SEP-2243 `Mcp-Param-*` mirroring read. New exports: `ResponseCacheStore`, `CacheKey`, `CacheEntry`, `CacheScope`, `MaybePromise`, `InMemoryResponseCacheStore`; new `ClientOptions.responseCacheStore` / `ClientOptions.listMaxPages` (caps the auto-aggregate walk at 64 pages by default; throws `SdkError` with `SdkErrorCode.ListPaginationExceeded` on overrun so a partial aggregate is never cached). The store interface is async-ready (`MaybePromise<…>`); the in-memory default stays synchronous. **A store instance must not be shared across `Client` instances at all in v2.0.x** — entries are keyed by method only (server-identity confusion + `clear()`/`evict()` cross-talk); per-principal partitioning that enables safe sharing arrives with the full caching engine.

docs/client.md

@@ -13,7 +13,7 @@ A client connects to a server, discovers what it offers — tools, resources, pr
 The examples below use these imports. Adjust based on which features and transport you need:
 
 ```ts source="../examples/guides/clientGuide.examples.ts#imports"
-import type { AuthProvider, Prompt, Resource, Tool } from '@modelcontextprotocol/client';
+import type { AuthProvider } from '@modelcontextprotocol/client';
 import {
     applyMiddlewares,
     Client,
@@ -252,20 +252,14 @@ For manual control over the token exchange steps, use the Layer 2 utilities from
 
 Tools are callable actions offered by servers — discovering and invoking them is usually how your client enables an LLM to take action (see [Tools](https://modelcontextprotocol.io/docs/learn/server-concepts#tools) in the MCP overview).
 
-Use {@linkcode @modelcontextprotocol/client!client/client.Client#listTools | listTools()} to discover available tools, and {@linkcode @modelcontextprotocol/client!client/client.Client#callTool | callTool()} to invoke one. Results may be paginated — loop on `nextCursor` to collect
-all pages:
+Use {@linkcode @modelcontextprotocol/client!client/client.Client#listTools | listTools()} to discover available tools, and {@linkcode @modelcontextprotocol/client!client/client.Client#callTool | callTool()} to invoke one. `listTools()` walks every page on your behalf and returns
+the complete list (pass an explicit `{ cursor }` for per-page control):
 
 ```ts source="../examples/guides/clientGuide.examples.ts#callTool_basic"
-const allTools: Tool[] = [];
-let toolCursor: string | undefined;
-do {
-    const { tools, nextCursor } = await client.listTools({ cursor: toolCursor });
-    allTools.push(...tools);
-    toolCursor = nextCursor;
-} while (toolCursor);
+const { tools } = await client.listTools();
 console.log(
     'Available tools:',
-    allTools.map(t => t.name)
+    tools.map(t => t.name)
 );
 
 const result = await client.callTool({
@@ -311,20 +305,14 @@ console.log(result.content);
 
 Resources are read-only data — files, database schemas, configuration — that your application can retrieve from a server and attach as context for the model (see [Resources](https://modelcontextprotocol.io/docs/learn/server-concepts#resources) in the MCP overview).
 
-Use {@linkcode @modelcontextprotocol/client!client/client.Client#listResources | listResources()} and {@linkcode @modelcontextprotocol/client!client/client.Client#readResource | readResource()} to discover and read server-provided data. Results may be paginated — loop on
-`nextCursor` to collect all pages:
+Use {@linkcode @modelcontextprotocol/client!client/client.Client#listResources | listResources()} and {@linkcode @modelcontextprotocol/client!client/client.Client#readResource | readResource()} to discover and read server-provided data. `listResources()` walks every page on your
+behalf and returns the complete list (pass an explicit `{ cursor }` for per-page control):
 
 ```ts source="../examples/guides/clientGuide.examples.ts#readResource_basic"
-const allResources: Resource[] = [];
-let resourceCursor: string | undefined;
-do {
-    const { resources, nextCursor } = await client.listResources({ cursor: resourceCursor });
-    allResources.push(...resources);
-    resourceCursor = nextCursor;
-} while (resourceCursor);
+const { resources } = await client.listResources();
 console.log(
     'Available resources:',
-    allResources.map(r => r.name)
+    resources.map(r => r.name)
 );
 
 const { contents } = await client.readResource({ uri: 'config://app' });
@@ -357,20 +345,14 @@ await client.unsubscribeResource({ uri: 'config://app' });
 
 Prompts are reusable message templates that servers offer to help structure interactions with models (see [Prompts](https://modelcontextprotocol.io/docs/learn/server-concepts#prompts) in the MCP overview).
 
-Use {@linkcode @modelcontextprotocol/client!client/client.Client#listPrompts | listPrompts()} and {@linkcode @modelcontextprotocol/client!client/client.Client#getPrompt | getPrompt()} to list available prompts and retrieve them with arguments. Results may be paginated — loop on
-`nextCursor` to collect all pages:
+Use {@linkcode @modelcontextprotocol/client!client/client.Client#listPrompts | listPrompts()} and {@linkcode @modelcontextprotocol/client!client/client.Client#getPrompt | getPrompt()} to list available prompts and retrieve them with arguments. `listPrompts()` walks every page on
+your behalf and returns the complete list (pass an explicit `{ cursor }` for per-page control):
 
 ```ts source="../examples/guides/clientGuide.examples.ts#getPrompt_basic"
-const allPrompts: Prompt[] = [];
-let promptCursor: string | undefined;
-do {
-    const { prompts, nextCursor } = await client.listPrompts({ cursor: promptCursor });
-    allPrompts.push(...prompts);
-    promptCursor = nextCursor;
-} while (promptCursor);
+const { prompts } = await client.listPrompts();
 console.log(
     'Available prompts:',
-    allPrompts.map(p => p.name)
+    prompts.map(p => p.name)
 );
 
 const { messages } = await client.getPrompt({

docs/migration-SKILL.md

@@ -560,6 +560,8 @@ side: auto-fulfilment is on by default (`ClientOptions.inputRequired`, `maxRound
 
 `Client.listPrompts()`, `listResources()`, `listResourceTemplates()`, `listTools()` now return empty results when the server lacks the corresponding capability (instead of sending the request). Set `enforceStrictCapabilities: true` in `ClientOptions` to throw an error instead.
 
+`Client.listTools()`, `listPrompts()`, `listResources()`, `listResourceTemplates()` called without a `cursor` now auto-aggregate every page and return the complete result (`nextCursor: undefined`); an explicit `{ cursor }` string still returns one page. Manual `do { … } while (cursor !== undefined)` loops keep working (the first call returns everything and the loop exits after one iteration) — replace them with the bare no-arg call. New `ClientOptions.listMaxPages` (default 64) caps the aggregate walk only; overrun throws `SdkError` (`SdkErrorCode.ListPaginationExceeded`).
+
 ### Server (Streamable HTTP transport)
 
 No code changes required; these are wire-behavior notes:

docs/migration.md

@@ -553,6 +553,28 @@ const client = new Client(
 );
 ```
 
+### Client list methods auto-aggregate pagination
+
+`Client.listTools()`, `listPrompts()`, `listResources()`, and `listResourceTemplates()` called **without a `cursor`** now walk every page on your behalf and return the complete aggregated result with `nextCursor: undefined`. This matches the C#, Java, and mcp.d SDKs. Passing an explicit `{ cursor }` string still fetches a single page (the v1 per-page contract).
+
+Existing manual pagination loops keep working — the first iteration returns everything and the loop exits after one pass — but they can now be deleted:
+
+```typescript
+// v1 — manual pagination loop
+const allTools: Tool[] = [];
+let cursor: string | undefined;
+do {
+    const { tools, nextCursor } = await client.listTools({ cursor });
+    allTools.push(...tools);
+    cursor = nextCursor;
+} while (cursor !== undefined);
+
+// v2 — auto-aggregated
+const { tools } = await client.listTools();
+```
+
+The auto-aggregate walk is capped at `ClientOptions.listMaxPages` pages (default 64; `0` disables) and throws an `SdkError` with `SdkErrorCode.ListPaginationExceeded` if the server's pagination does not converge, so a partial aggregate is never returned. The cap applies only to the no-`cursor` aggregate path; explicit per-page calls are never capped. The aggregated result is also written to the client's response cache (the source for `callTool`'s output-schema validation and SEP-2243 header mirroring).
+
 ### `InMemoryTransport` moved
 
 `InMemoryTransport` is now exported from `@modelcontextprotocol/client` and `@modelcontextprotocol/server` (both re-export it). It is still intended for in-process client-server connections and testing.

examples/guides/clientGuide.examples.ts

@@ -8,7 +8,7 @@
  */
 
 //#region imports
-import type { AuthProvider, Prompt, Resource, Tool } from '@modelcontextprotocol/client';
+import type { AuthProvider } from '@modelcontextprotocol/client';
 import {
     applyMiddlewares,
     Client,
@@ -196,16 +196,10 @@ async function auth_crossAppAccess(getIdToken: () => Promise<string>) {
 /** Example: List and call tools. */
 async function callTool_basic(client: Client) {
     //#region callTool_basic
-    const allTools: Tool[] = [];
-    let toolCursor: string | undefined;
-    do {
-        const { tools, nextCursor } = await client.listTools({ cursor: toolCursor });
-        allTools.push(...tools);
-        toolCursor = nextCursor;
-    } while (toolCursor);
+    const { tools } = await client.listTools();
     console.log(
         'Available tools:',
-        allTools.map(t => t.name)
+        tools.map(t => t.name)
     );
 
     const result = await client.callTool({
@@ -251,16 +245,10 @@ async function callTool_progress(client: Client) {
 /** Example: List and read resources. */
 async function readResource_basic(client: Client) {
     //#region readResource_basic
-    const allResources: Resource[] = [];
-    let resourceCursor: string | undefined;
-    do {
-        const { resources, nextCursor } = await client.listResources({ cursor: resourceCursor });
-        allResources.push(...resources);
-        resourceCursor = nextCursor;
-    } while (resourceCursor);
+    const { resources } = await client.listResources();
     console.log(
         'Available resources:',
-        allResources.map(r => r.name)
+        resources.map(r => r.name)
     );
 
     const { contents } = await client.readResource({ uri: 'config://app' });
@@ -290,16 +278,10 @@ async function subscribeResource_basic(client: Client) {
 /** Example: List and get prompts. */
 async function getPrompt_basic(client: Client) {
     //#region getPrompt_basic
-    const allPrompts: Prompt[] = [];
-    let promptCursor: string | undefined;
-    do {
-        const { prompts, nextCursor } = await client.listPrompts({ cursor: promptCursor });
-        allPrompts.push(...prompts);
-        promptCursor = nextCursor;
-    } while (promptCursor);
+    const { prompts } = await client.listPrompts();
     console.log(
         'Available prompts:',
-        allPrompts.map(p => p.name)
+        prompts.map(p => p.name)
     );
 
     const { messages } = await client.getPrompt({

packages/client/src/client/client.examples.ts

@@ -7,8 +7,6 @@
  * @module
  */
 
-import type { Prompt, Resource, Tool } from '@modelcontextprotocol/core';
-
 import { Client } from './client.js';
 import { SSEClientTransport } from './sse.js';
 import { StdioClientTransport } from './stdio.js';
@@ -137,61 +135,43 @@ function Client_setRequestHandler_sampling(client: Client) {
 }
 
 /**
- * Example: List tools with cursor-based pagination.
+ * Example: List tools (auto-aggregated across pages).
  */
 async function Client_listTools_pagination(client: Client) {
     //#region Client_listTools_pagination
-    const allTools: Tool[] = [];
-    let cursor: string | undefined;
-    // Note: an empty-string cursor is valid and does not signal the end of results.
-    do {
-        const { tools, nextCursor } = await client.listTools({ cursor });
-        allTools.push(...tools);
-        cursor = nextCursor;
-    } while (cursor !== undefined);
+    // No cursor → all pages aggregated for you.
+    const { tools } = await client.listTools();
     console.log(
         'Available tools:',
-        allTools.map(t => t.name)
+        tools.map(t => t.name)
     );
     //#endregion Client_listTools_pagination
 }
 
 /**
- * Example: List prompts with cursor-based pagination.
+ * Example: List prompts (auto-aggregated across pages).
  */
 async function Client_listPrompts_pagination(client: Client) {
     //#region Client_listPrompts_pagination
-    const allPrompts: Prompt[] = [];
-    let cursor: string | undefined;
-    // Note: an empty-string cursor is valid and does not signal the end of results.
-    do {
-        const { prompts, nextCursor } = await client.listPrompts({ cursor });
-        allPrompts.push(...prompts);
-        cursor = nextCursor;
-    } while (cursor !== undefined);
+    // No cursor → all pages aggregated for you.
+    const { prompts } = await client.listPrompts();
     console.log(
         'Available prompts:',
-        allPrompts.map(p => p.name)
+        prompts.map(p => p.name)
     );
     //#endregion Client_listPrompts_pagination
 }
 
 /**
- * Example: List resources with cursor-based pagination.
+ * Example: List resources (auto-aggregated across pages).
  */
 async function Client_listResources_pagination(client: Client) {
     //#region Client_listResources_pagination
-    const allResources: Resource[] = [];
-    let cursor: string | undefined;
-    // Note: an empty-string cursor is valid and does not signal the end of results.
-    do {
-        const { resources, nextCursor } = await client.listResources({ cursor });
-        allResources.push(...resources);
-        cursor = nextCursor;
-    } while (cursor !== undefined);
+    // No cursor → all pages aggregated for you.
+    const { resources } = await client.listResources();
     console.log(
         'Available resources:',
-        allResources.map(r => r.name)
+        resources.map(r => r.name)
     );
     //#endregion Client_listResources_pagination
 }