# JSON-RPC Methods

> What the handler answers, and on which era.

Every method below is implemented for you. You never register a method — you declare tools, resources, and prompts, and the methods that expose them exist.

## Shared

| Method                     | Answers with                                   |
| -------------------------- | ---------------------------------------------- |
| `tools/list`               | Declared tools, paginated, schemas resolved    |
| `tools/call`               | Tool result, after validating `arguments`      |
| `resources/list`           | Declared resources, paginated                  |
| `resources/read`           | Resource contents; falls back to URI templates |
| `resources/templates/list` | Declared resource templates, paginated         |
| `prompts/list`             | Declared prompts, paginated                    |
| `prompts/get`              | Prompt messages, after checking required args  |
| `completion/complete`      | Values from a `complete` callback              |

## Modern Only

| Method                 | Answers with                                               |
| ---------------------- | ---------------------------------------------------------- |
| `server/discover`      | Versions, capabilities, instructions, identity (cacheable) |
| `subscriptions/listen` | A long-lived SSE stream of opted-in notifications          |

## Legacy Only

| Method                      | Answers with                                                         |
| --------------------------- | -------------------------------------------------------------------- |
| `initialize`                | Negotiated version, capabilities, `serverInfo`                       |
| `notifications/initialized` | Accepted, no-op                                                      |
| `ping`                      | Empty result                                                         |
| `notifications/cancelled`   | Aborts the named in-flight request (alias: `notifications/canceled`) |
| `notifications/progress`    | Invokes `onProgress`                                                 |
| `resources/subscribe`       | Invokes `onSubscribe`                                                |
| `resources/unsubscribe`     | Invokes `onUnsubscribe`                                              |
| `logging/setLevel`          | Invokes `onLogLevelSet`                                              |

An unknown method is `-32601`, with HTTP `404` on the modern era.

## Pagination

`tools/list`, `resources/list`, `resources/templates/list`, and `prompts/list` are cursor-paginated. Clients pass the `nextCursor` from the previous page; the cursor is opaque and validated, so a malformed one is `-32602` rather than an unbounded read.

```sh
curl -X POST http://localhost:3000/mcp \
  -H 'content-type: application/json' \
  -d '{ "jsonrpc": "2.0", "id": 1, "method": "tools/list",
        "params": { "cursor": "eyJvZmZzZXQiOjEwfQ==" } }'
```

## Capabilities

Capabilities are derived, never declared by hand:

| Capability            | Advertised when                                           |
| --------------------- | --------------------------------------------------------- |
| `tools`               | at least one tool                                         |
| `resources`           | at least one resource or resource template                |
| `prompts`             | at least one prompt                                       |
| `completions`         | any prompt argument or template has a `complete` callback |
| `logging`             | `onLogLevelSet` (legacy) or `logging: true` (modern)      |
| `resources.subscribe` | `onSubscribe` (legacy) or `onListen` (modern)             |
| `*.listChanged`       | always (legacy) · `onListen` (modern)                     |
| `extensions`          | `extensions` is set (modern)                              |

:read-more{to="/guide/eras" title="Protocol eras"}