docs: comprehensive feature documentation for SEP-1730 Tier 1

README.md

@@ -154,6 +154,7 @@ For more details on how to run these examples (including recommended commands an
     - [docs/server.md](docs/server.md) – building and running MCP servers, transports, tools/resources/prompts, CORS, DNS rebinding, and multi-node deployment.
     - [docs/client.md](docs/client.md) – using the high-level client, transports, backwards compatibility, and OAuth helpers.
     - [docs/capabilities.md](docs/capabilities.md) – sampling, elicitation (form and URL), and experimental task-based execution.
+    - [docs/protocol.md](docs/protocol.md) – protocol features: ping, progress, cancellation, pagination, capability negotiation, and JSON Schema.
     - [docs/faq.md](docs/faq.md) – environment and troubleshooting FAQs (including Node.js Web Crypto support).
 - External references:
     - [Model Context Protocol documentation](https://modelcontextprotocol.io)

docs/capabilities.md

@@ -27,6 +27,99 @@ Runnable example:
 
 The `simpleStreamableHttp` server also includes a `collect-user-info` tool that demonstrates how to drive elicitation from a tool and handle the response.
 
+#### Schema validation
+
+Elicitation schemas support validation constraints on each field. The server validates responses automatically against the `requestedSchema` using the SDK's JSON Schema validator.
+
+```typescript
+const result = await server.server.elicitInput({
+    mode: 'form',
+    message: 'Enter your details:',
+    requestedSchema: {
+        type: 'object',
+        properties: {
+            email: {
+                type: 'string',
+                title: 'Email',
+                format: 'email',
+                minLength: 5
+            },
+            age: {
+                type: 'integer',
+                title: 'Age',
+                minimum: 0,
+                maximum: 150
+            }
+        },
+        required: ['email']
+    }
+});
+```
+
+String fields support `minLength`, `maxLength`, and `format` (`'email'`, `'uri'`, `'date'`, `'date-time'`). Number fields support `minimum` and `maximum`.
+
+#### Default values
+
+Schema properties can include `default` values. When the client declares the `applyDefaults` capability, the SDK automatically fills in defaults for fields the user doesn't provide.
+
+> **Note:** `applyDefaults` is a TypeScript SDK extension — it is not part of the MCP protocol specification.
+
+```typescript
+// Client declares applyDefaults:
+const client = new Client(
+  { name: 'my-client', version: '1.0.0' },
+  { capabilities: { elicitation: { form: { applyDefaults: true } } } }
+);
+
+// Server schema with defaults:
+requestedSchema: {
+  type: 'object',
+  properties: {
+    newsletter: { type: 'boolean', title: 'Newsletter', default: false },
+    theme: { type: 'string', title: 'Theme', default: 'dark' }
+  }
+}
+```
+
+#### Enum values
+
+Elicitation schemas support several enum patterns for single-select and multi-select fields:
+
+```typescript
+requestedSchema: {
+  type: 'object',
+  properties: {
+    // Simple enum (untitled options)
+    color: {
+      type: 'string',
+      title: 'Favorite Color',
+      enum: ['red', 'green', 'blue'],
+      default: 'blue'
+    },
+    // Titled enum with display labels
+    priority: {
+      type: 'string',
+      title: 'Priority',
+      oneOf: [
+        { const: 'low', title: 'Low Priority' },
+        { const: 'medium', title: 'Medium Priority' },
+        { const: 'high', title: 'High Priority' }
+      ]
+    },
+    // Multi-select
+    tags: {
+      type: 'array',
+      title: 'Tags',
+      items: { type: 'string', enum: ['frontend', 'backend', 'docs'] },
+      minItems: 1,
+      maxItems: 3
+    }
+  }
+}
+```
+
+For a full example with validation, defaults, and enums, see [`elicitationFormExample.ts`](../src/examples/server/elicitationFormExample.ts).
+
 ### URL elicitation
 
 URL elicitation is designed for sensitive data and secure web‑based flows (e.g., collecting an API key, confirming a payment, or doing third‑party OAuth). Instead of returning form data, the server asks the client to open a URL and the rest of the flow happens in the browser.
@@ -46,6 +139,23 @@ Key points:
 
 Sensitive information **must not** be collected via form elicitation; always use URL elicitation or out‑of‑band flows for secrets.
 
+#### Complete notification
+
+When a URL elicitation flow finishes (the user completes the browser-based action), the server sends a `notifications/elicitation/complete` notification to the client. This tells the client the out-of-band flow is done and any pending UI can be dismissed.
+
+Use `createElicitationCompletionNotifier` on the low-level server to create a callback that sends this notification:
+
+```typescript
+// Create a notifier for a specific elicitation:
+const notifyComplete = server.server.createElicitationCompletionNotifier('setup-123');
+
+// Later, when the browser flow completes (e.g. via webhook):
+await notifyComplete();
+// Client receives: { method: 'notifications/elicitation/complete', params: { elicitationId: 'setup-123' } }
+```
+
+See [`elicitationUrlExample.ts`](../src/examples/server/elicitationUrlExample.ts) for a full working example.
+
 ## Task-based execution (experimental)
 
 Task-based execution enables “call-now, fetch-later” patterns for long-running operations. Instead of returning a result immediately, a tool creates a task that can be polled or resumed later.
@@ -70,7 +180,7 @@ For a runnable example that uses the in-memory store shipped with the SDK, see:
 On the client, you use:
 
 - `client.experimental.tasks.callToolStream(...)` to start a tool call that may create a task and emit status updates over time.
-- `client.getTask(...)` and `client.getTaskResult(...)` to check status and fetch results after reconnecting.
+- `client.experimental.tasks.getTask(...)` and `client.experimental.tasks.getTaskResult(...)` to check status and fetch results after reconnecting.
 
 The interactive client in:
 

docs/client.md

@@ -58,3 +58,53 @@ These examples show how to:
 - Perform dynamic client registration if needed.
 - Acquire access tokens.
 - Attach OAuth credentials to Streamable HTTP requests.
+
+## stdio transport
+
+Use `StdioClientTransport` to connect to a server that runs as a local child process:
+
+```typescript
+import { Client } from '@modelcontextprotocol/sdk/client/index.js';
+import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js';
+
+const transport = new StdioClientTransport({
+    command: 'node',
+    args: ['server.js'],
+    env: { NODE_ENV: 'production' },
+    cwd: '/path/to/server'
+});
+
+const client = new Client({ name: 'my-client', version: '1.0.0' });
+await client.connect(transport);
+// connect() calls transport.start() automatically, spawning the child process
+```
+
+The transport communicates over the child process's stdin/stdout using JSON-RPC. The `stderr` option controls where the child's stderr goes (defaults to `'inherit'`).
+
+## Roots
+
+Roots let a client expose filesystem locations to the server, so the server knows which directories or files are relevant. Declare the `roots` capability and register a handler:
+
+```typescript
+import { Client } from '@modelcontextprotocol/sdk/client/index.js';
+import { ListRootsRequestSchema } from '@modelcontextprotocol/sdk/types.js';
+
+const client = new Client({ name: 'my-client', version: '1.0.0' }, { capabilities: { roots: { listChanged: true } } });
+
+client.setRequestHandler(ListRootsRequestSchema, async () => {
+    return {
+        roots: [
+            { uri: 'file:///home/user/project', name: 'My Project' },
+            { uri: 'file:///home/user/data', name: 'Data Directory' }
+        ]
+    };
+});
+```
+
+When the set of roots changes, notify the server so it can re-query:
+
+```typescript
+await client.sendRootsListChanged();
+```
+
+Root URIs must use the `file://` scheme. The `listChanged: true` capability flag is required to send change notifications.

docs/protocol.md

@@ -0,0 +1,200 @@
+## Protocol features
+
+This page covers cross-cutting protocol mechanics that apply to both clients and servers.
+
+## Ping
+
+Both client and server expose a `ping()` method for health checks. The remote side responds automatically — no handler registration is needed.
+
+```typescript
+// Client pinging the server:
+await client.ping();
+
+// With a timeout (milliseconds):
+await client.ping({ timeout: 5000 });
+
+// Server pinging the client (via the low-level server, no timeout option):
+await server.server.ping();
+```
+
+## Progress notifications
+
+Long-running requests can report progress to the caller. The SDK handles `progressToken` assignment automatically when you provide an `onprogress` callback.
+
+**Receiving progress** (client side):
+
+```typescript
+const result = await client.callTool({ name: 'long-task', arguments: {} }, CallToolResultSchema, {
+    onprogress: progress => {
+        // progress has: { progress: number, total?: number, message?: string }
+        console.log(`${progress.progress}/${progress.total}: ${progress.message}`);
+    },
+    timeout: 30000,
+    resetTimeoutOnProgress: true
+});
+```
+
+**Sending progress** (server side, from a tool handler):
+
+```typescript
+server.registerTool(
+    'count',
+    {
+        description: 'Count to N with progress updates',
+        inputSchema: { n: z.number() }
+    },
+    async ({ n }, extra) => {
+        for (let i = 1; i <= n; i++) {
+            if (extra._meta?.progressToken !== undefined) {
+                await extra.sendNotification({
+                    method: 'notifications/progress',
+                    params: {
+                        progressToken: extra._meta.progressToken,
+                        progress: i,
+                        total: n,
+                        message: `Counting: ${i}/${n}`
+                    }
+                });
+            }
+            await new Promise(resolve => setTimeout(resolve, 100));
+        }
+        return { content: [{ type: 'text', text: `Counted to ${n}` }] };
+    }
+);
+```
+
+For a runnable example, see [`progressExample.ts`](../src/examples/server/progressExample.ts).
+
+## Cancellation
+
+Requests can be cancelled by the caller using an `AbortSignal`. The SDK sends a `notifications/cancelled` message to the remote side and aborts the handler via its `signal`.
+
+**Client cancelling a request**:
+
+```typescript
+const controller = new AbortController();
+
+const resultPromise = client.callTool({ name: 'slow-tool', arguments: {} }, CallToolResultSchema, { signal: controller.signal });
+
+// Cancel after 5 seconds:
+setTimeout(() => controller.abort('User cancelled'), 5000);
+```
+
+**Server handler responding to cancellation**:
+
+```typescript
+server.setRequestHandler(CallToolRequestSchema, async (request, extra) => {
+    for (let i = 0; i < 100; i++) {
+        if (extra.signal.aborted) {
+            return { content: [{ type: 'text', text: 'Cancelled' }], isError: true };
+        }
+        await doWork();
+    }
+    return { content: [{ type: 'text', text: 'Done' }] };
+});
+```
+
+## Pagination
+
+All list methods (`listTools`, `listPrompts`, `listResources`, `listResourceTemplates`) support cursor-based pagination. Pass `cursor` from the previous response's `nextCursor` to fetch the next page.
+
+```typescript
+let cursor: string | undefined;
+const allTools: Tool[] = [];
+
+do {
+    const result = await client.listTools({ cursor });
+    allTools.push(...result.tools);
+    cursor = result.nextCursor;
+} while (cursor);
+```
+
+The same pattern applies to `listPrompts`, `listResources`, and `listResourceTemplates`.
+
+## Capability negotiation
+
+Both client and server declare their capabilities during the `initialize` handshake. The SDK enforces these — attempting to use an undeclared capability throws an error.
+
+**Client capabilities** are set at construction time:
+
+```typescript
+const client = new Client(
+    { name: 'my-client', version: '1.0.0' },
+    {
+        capabilities: {
+            roots: { listChanged: true },
+            sampling: {},
+            elicitation: { form: {} }
+        }
+    }
+);
+```
+
+After connecting, inspect what the server supports:
+
+```typescript
+await client.connect(transport);
+
+const caps = client.getServerCapabilities();
+if (caps?.tools) {
+    const tools = await client.listTools();
+}
+if (caps?.resources?.subscribe) {
+    // server supports resource subscriptions
+}
+```
+
+**Server capabilities** are inferred from registered handlers. When using `McpServer`, capabilities are set automatically based on what you register (tools, resources, prompts). With the low-level `Server`, you declare them in the constructor.
+
+## Protocol version negotiation
+
+The SDK automatically negotiates protocol versions during `initialize`. The client sends `LATEST_PROTOCOL_VERSION` and the server responds with the highest mutually supported version.
+
+Supported versions are defined in `SUPPORTED_PROTOCOL_VERSIONS` (currently `2025-11-25`, `2025-06-18`, `2025-03-26`, `2024-11-05`, `2024-10-07`). If the server responds with an unsupported version, the client throws an error.
+
+Version negotiation is handled automatically by `client.connect()`. After connecting, you can inspect the result:
+
+```typescript
+await client.connect(transport);
+
+const serverVersion = client.getServerVersion();
+// { name: 'my-server', version: '1.0.0' }
+
+const serverCaps = client.getServerCapabilities();
+// { tools: { listChanged: true }, resources: { subscribe: true }, ... }
+```
+
+## JSON Schema 2020-12
+
+MCP uses JSON Schema 2020-12 for tool input and output schemas. When using `McpServer` with Zod, schemas are converted to JSON Schema automatically:
+
+```typescript
+server.registerTool(
+    'calculate',
+    {
+        description: 'Add two numbers',
+        inputSchema: { a: z.number(), b: z.number() }
+    },
+    async ({ a, b }) => ({
+        content: [{ type: 'text', text: String(a + b) }]
+    })
+);
+```
+
+With the low-level `Server`, you provide JSON Schema directly:
+
+```typescript
+{
+  name: 'calculate',
+  inputSchema: {
+    type: 'object',
+    properties: {
+      a: { type: 'number' },
+      b: { type: 'number' }
+    },
+    required: ['a', 'b']
+  }
+}
+```
+
+The SDK validates tool outputs against `outputSchema` (when provided) using a pluggable JSON Schema validator. The default validator uses Ajv; a Cloudflare Workers-compatible alternative is available via `CfWorkerJsonSchemaValidator`.