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# Migrate @mastra/mcp from v1 to v2

`@mastra/mcp` 2.0 serves the MCP **2026-07-28** revision only. Servers no longer negotiate older protocol revisions. Every request is self-contained: the `initialize` handshake, session header, standalone HTTP+SSE transport and server-initiated requests are gone. A tool, resource or prompt that needs input from the caller calls `suspend()`. The server answers with a native `input_required` continuation and runs the handler again with the caller's answer in `resumeData`.

The client speaks 2026-07-28 and, by default, probes each server and speaks whichever revision it offers, so one `MCPClient` can reach upgraded and third-party servers alike. Features that older revisions lack fail with an explicit error on a legacy-negotiated connection instead of being emulated.

If you need to keep **serving** pre-2026 clients, stay on `@mastra/mcp` 1.x. It remains supported against current `@mastra/core`, and a Mastra instance can register 1.x and 2.x servers side by side.

Streamable HTTP still streams responses as Server-Sent Events. What's removed is the standalone `GET /sse` + `POST /messages` transport, not SSE framing.

## Changed

### `@mastra/core` peer range

`@mastra/mcp` 2.0 requires `@mastra/core` 1.68 or newer, which adds the shared server contract (`mcpVersion`, `MCPToolExecutionResultV2`, `context.mcp.protocolVersion`). Update both packages together.

```diff
- "@mastra/core": "^1.60.0",
- "@mastra/mcp": "^1.17.0"
+ "@mastra/core": "^1.68.0",
+ "@mastra/mcp": "^2.0.0"
```

### Tools that ask the caller for input suspend and resume

In 1.x a tool asked for input through `context.mcp.elicitation.sendRequest()` and awaited the answer while the request stayed open. In 2.0 the tool calls `context.suspend(payload)` and returns; the server ends the request as `input_required`, and when the caller answers, the tool runs again with `context.resumeData` (the answer, validated against `resumeSchema`) and `context.suspendPayload` (what it suspended with, validated against `suspendSchema`). This is the same `suspend`/`resume` vocabulary agents and workflows already use, so one `createTool` definition serves all three.

To migrate, move each `sendRequest` into a suspension. Put the state the next round needs in the suspend payload and branch on it when the tool resumes. The server never replays earlier rounds: each round sees only the previous payload and the current answer.

```diff
export const bookDelivery = createTool({
    id: 'bookDelivery',
    inputSchema: z.object({ orderId: z.string() }),
    outputSchema: z.object({ confirmed: z.boolean() }),
+   suspendSchema: z.object({ phase: z.literal('address'), message: z.string() }),
+   resumeSchema: z.object({ address: z.string() }),
    execute: async ({ orderId }, context) => {
-     const answer = await context.mcp!.elicitation.sendRequest({
-       message: 'Delivery address?',
-       requestedSchema: addressSchema,
-     });
-     if (answer.action !== 'accept') return { confirmed: false };
-     await book(orderId, answer.content.address);
-     return { confirmed: true };
+     if (!context.resumeData) {
+       await context.suspend?.({ phase: 'address', message: 'Delivery address?' });
+       return;
+     }
+     await book(orderId, context.resumeData.address);
+     return { confirmed: true };
    },
  });
```

`resumeSchema` becomes the form the caller fills in, so it must describe a flat object of primitives. A caller that declines or cancels the form ends the call with an error, and the tool doesn't run again.

The continuation travels as an opaque `requestState` string that the client echoes byte for byte. The server signs it, and rejects a tampered, expired or foreign state (a different tool, different arguments or a different caller) before your handler runs. The caller is the token subject when the authorization layer provides one, otherwise the `id` of the user `mapAuthInfoToUser` returns, otherwise the bearer token itself, so two users behind the same OAuth client can't resume each other's rounds. On a server without authorization every caller shares one anonymous principal, so a `requestState` behaves like a bearer credential until its `ttlSeconds` expire: anyone who obtains it can answer the round. Put tools whose suspensions carry authority (writes, purchases, account changes) behind authorization. The payload is signed, not encrypted, so keep it small and non-secret (IDs and phase, not confidential data). Set `requestState: { key }` from the environment so every instance that may answer a continuation shares the key. Without it the server generates a key per process and continuations only succeed on that process.

```diff
const server = new MCPServer({
    name: 'booking',
    version: '2.0.0',
    tools: { bookDelivery },
+   requestState: { key: process.env.MCP_REQUEST_STATE_KEY!, ttlSeconds: 600 },
  });
```

### `context.mcp` is the same object, with server-initiated requests removed

Tools still receive `context.mcp` on a 2.0 server: `extra` (cancellation `signal`, `requestId`, `authInfo`, `_meta`), `log` and `progress` work as before, and `context.mcp.protocolVersion` is `'2026-07-28'`. The members that relied on server-initiated requests are deprecated and throw on a 2.0 server with a message that names the replacement: `elicitation.sendRequest` (use `suspend`), `extra.sendRequest` and `extra.sendNotification` (use `log` and `progress`).

### `executeTool` reports a suspension

`server.executeTool()` and the Mastra REST route `POST /api/mcp/:serverId/tools/:toolId/execute` return `{ status: 'completed', output }` for a finished call and `{ status: 'suspended', suspendPayload, resumeSchema }` when the tool asked for input. Continue by posting the same `data` again with `resumeData` and the echoed `suspendPayload`. Invalid `resumeData` rejects the call.

```diff
- const output = await server.executeTool('bookDelivery', { orderId });
+ const result = await server.executeTool('bookDelivery', { orderId });
+ if (result.status === 'suspended') {
+   const answer = await askUser(result.suspendPayload, result.resumeSchema);
+   await server.executeTool('bookDelivery', { orderId }, { resumeData: answer, suspendPayload: result.suspendPayload });
+ }
```

### Resource and prompt callbacks can suspend too

`getResourceContent` and `getPromptMessages` receive `{ extra, requestContext, suspend, resumeData, suspendPayload }` alongside their existing parameters. `extra` is the same protocol context tools see as `context.mcp.extra`, and `requestContext` is the trusted application context that already carries `authInfo` and the user mapped by `mapAuthInfoToUser`. Declare `resumeSchema` on `resources` or `prompts` to make `suspend` usable.

```diff
resources: {
    listResources: async ({ requestContext }) => listFor(requestContext.get('authInfo')?.clientId),
-   getResourceContent: async ({ uri, extra }) => read(uri, extra?.signal),
+   resumeSchema: z.object({ reader: z.string() }),
+   getResourceContent: async ({ uri, extra, suspend, resumeData }) => {
+     if (!resumeData) return suspend({ message: 'Who is reading?' });
+     return read(uri, resumeData.reader, extra.signal);
+   },
  },
```

### Per-request logging replaces session log levels

Servers no longer accept `logging/setLevel` or keep a log level per connection. A client opts in per request by sending the `io.modelcontextprotocol/logLevel` metadata key, and the server delivers `notifications/message` for that request only, filtered to the requested severity. A later round of the same tool call is a new request: it must opt in again. Tools keep logging through `context.mcp.log(level, message, data)`. The Mastra logger and observability are unaffected.

On the client, `enableServerLogs` (default `true`) attaches the metadata key to every request at `serverLogLevel` (default `'info'`). Set `enableServerLogs: false` to receive nothing. Delivered messages still reach your `logger` handler.

```diff
servers: {
    weather: {
      url: new URL('http://localhost:4111/api/mcp/weather/mcp'),
      enableServerLogs: true,
+     serverLogLevel: 'warning',
      logger: msg => console.log(msg.serverName, msg.level, msg.message),
    },
  },
```

### Resource subscriptions keep their API and ride one listen stream

`resources.subscribe` and `resources.unsubscribe` keep their signatures. Under the hood the client carries every subscription and list-changed handler on a single `subscriptions/listen` stream per server, replaces the stream when the set changes, and reopens it after a reconnect. Register handlers before subscribing so nothing is missed. A subscription the server declines rejects and leaves earlier subscriptions in place.

```ts
await mcp.resources.onUpdated('weather', ({ uri }) => refresh(uri))
await mcp.resources.subscribe('weather', 'weather://forecast')
// later
await mcp.resources.unsubscribe('weather', 'weather://forecast')
```

### Client input handlers are configured per server

The client answered server elicitation with `mcp.elicitation.onRequest(serverName, handler)`. Because input requests are now embedded in `input_required` results, the handler is part of the server definition and receives one request at a time. Configuring it advertises the `elicitation.form` capability. Without a handler an `input_required` result is surfaced as an error rather than answered on your behalf.

```diff
const mcp = new MCPClient({
    servers: {
      booking: {
        url: new URL('http://localhost:4111/api/mcp/booking/mcp'),
+       inputRequests: async ({ key, params }) => askUser(key, params),
      },
    },
  });
- await mcp.elicitation.onRequest('booking', async params => askUser(params));
```

### Client `protocolVersion` pins instead of selecting a revision

The 1.x client accepted `protocolVersion: '2025-11-25' | '2026-07-28' | 'auto'`. The 2.0 client always speaks 2026-07-28 and, when the option is omitted, probes the server with `server/discover` and falls back to the `initialize` handshake for servers that haven't upgraded. Pin `'2026-07-28'` to skip the probe and fail on a legacy server, or `'legacy'` to skip the probe and use the handshake directly. The negotiated revision is cached per connection for reconnects and reported by `mcp.getServerProtocolVersions()`.

On a legacy-negotiated connection the shared verbs work (`tools/list`, `tools/call`, `resources/read`, `prompts/get`). Resource subscriptions, list-changed handlers and embedded input requests throw an error naming the negotiated revision.

```diff
servers: {
    thirdParty: {
      url: new URL('https://example.com/mcp'),
-     protocolVersion: 'auto',
+     protocolVersion: 'legacy', // optional: skip the probe for a server known not to have upgraded
    },
  },
```

### OAuth clients are pre-registered or use a Client ID Metadata Document

`MCPOAuthClientProvider` no longer registers clients dynamically. Pass either `clientInformation` for a client you registered with the authorization server, or `clientMetadataUrl` (SEP-991) so the server fetches your client metadata from an HTTPS URL. Constructing the provider with neither throws, and no request is ever sent to a `registration_endpoint`.

```diff
const authProvider = new MCPOAuthClientProvider({
    redirectUrl: 'http://localhost:3000/oauth/callback',
    clientMetadata: { client_name: 'My Agent', redirect_uris: ['http://localhost:3000/oauth/callback'] },
+   clientInformation: { client_id: process.env.MCP_OAUTH_CLIENT_ID! },
  });
```

Persisted credentials changed shape too: tokens are stored per authorization-server `issuer` (the SDK's `tokens(ctx)`/`saveTokens(tokens, ctx)` context) and the provider persists OAuth discovery state so the authorization code is only exchanged with the server that issued the redirect. Custom `OAuthStorage` backends keep the same key-value contract, but a storage namespace must not be shared between providers. `createOAuthCallbackServer` now also returns the RFC 9207 `iss` parameter. Pass it to the code exchange so the SDK can reject an issuer mismatch.

### `startHTTP` options

`startHTTP` keeps `url`, `httpPath`, `req` and `res`. The `options` object only carries request security (`enableDnsRebindingProtection`, `allowedHosts`, `allowedOrigins`). The session and serverless flags are gone because every request is stateless.

```diff
await server.startHTTP({
    url: new URL(req.url!, 'http://localhost'),
    httpPath: '/mcp',
    req,
    res,
-   options: { sessionIdGenerator: () => randomUUID(), serverless: false },
+   options: { enableDnsRebindingProtection: true, allowedHosts: ['localhost:4111'] },
  });
```

### Docs server `Prompt` metadata

`MastraPrompt` and its deprecated `version` field are gone; prompt providers return the SDK `Prompt` type, re-exported from `@mastra/mcp`.

```diff
- import type { MastraPrompt } from '@mastra/mcp';
+ import type { Prompt } from '@mastra/mcp';
```

## Removed

### Server `protocolVersion` option

Servers accepted `protocolVersion` (`'2025-11-25'`, `'2026-07-28'` or `'auto'`). Only `2026-07-28` is served now, exposed as the `MCP_PROTOCOL_VERSION` constant. Remove the option; a client that doesn't offer `2026-07-28` fails with an explicit negotiation error instead of a downgrade.

```diff
const server = new MCPServer({
    name: 'weather',
    version: '1.0.0',
-   protocolVersion: '2026-07-28',
    tools,
  });
```

### `startSSE`, `startHonoSSE`, `connectSSE` and the `/sse` + `/messages` routes

The standalone HTTP+SSE transport is no longer served, and the client no longer falls back to it when Streamable HTTP is unavailable. `startSSE` and `startHonoSSE` remain on the shared `MCPServerBase` for 1.x servers but reject on a 2.0 server. `connectSSE` is removed. Mastra server adapters answer `404` on `/sse` and `/messages` for 2.0 servers, and Studio no longer shows an SSE endpoint for them. Point every client at the `/mcp` endpoint.

```diff
- url: new URL('http://localhost:4111/api/mcp/weather/sse'),
+ url: new URL('http://localhost:4111/api/mcp/weather/mcp'),
```

### `handleServerlessRequest`, `sessionId`, `sessionIds`, `reconnectionOptions`, `eventSourceInit`

Requests are stateless, so there is nothing to resume or identify. `startHTTP` handles serverless and long-lived servers alike. Remove the session options from server and client definitions.

```diff
servers: {
    weather: {
      url: new URL('http://localhost:4111/api/mcp/weather/mcp'),
-     sessionId: savedSessionId,
-     reconnectionOptions: { maxRetries: 3 },
    },
  },
```

### `elicitation` actions on server and client

`server.elicitation.sendRequest()` and `mcp.elicitation.onRequest()` are removed. Suspend from the tool and configure `inputRequests` on the client.

### `roots` and `sampling`

Clients no longer advertise `roots`. `setRoots()` and `sendRootsListChanged()` are gone. Servers neither request sampling nor advertise it. A server that embeds a `roots/list` or `sampling/createMessage` request in `input_required` isn't answered: the client has no handler for those methods, so the call fails instead of fabricating a response.

### `logging/setLevel` and `sendLoggingMessage`

Servers keep the static `logging` capability required by the specification but reject `logging/setLevel` with method-not-found. `server.sendLoggingMessage()` and `server.getServer()` are removed. Log per request through `context.mcp.log` or keep using the Mastra logger.

### `resources/subscribe` and `resources/unsubscribe`

Legacy `resources/subscribe` is removed from both sides. `resources.subscribe` now uses `subscriptions/listen`.

### Dynamic client registration

`registerClient`, `OAuthClientRegistrationError` and the `saveClientInformation`-driven registration fallback are removed. See the OAuth section above for the replacement.

### Telling 1.x and 2.0 servers apart

Both extend the same `MCPServerBase`, and a 2.0 server sets `mcpVersion` to `2`. Use it to branch where the two differ, such as whether an `executeTool` result can be a suspension.

```diff
const server = mastra.getMCPServer('booking');
+ if (server?.mcpVersion === 2) { ... }
```