Provide roots

Deprecated — SEP-2577

Pass paths through tool arguments, resource URIs, or host configuration instead. Roots are deprecated as of protocol version 2026-07-28 (SEP-2577) and stay functional on 2025-era connections for at least twelve months — see the deprecated features registry.

Migrate away first

A root is a file:// URI the client hands to the server as a boundary for its file operations. The 2026-07-28 revision deprecates the request that carries them, and nothing replaces it — give the server its paths directly.

Send the path a call should act on as a tool argument (Tools), expose the locations the server owns as resources (Resources), or put fixed directories in the server's own configuration. The rest of this page covers the roots API for clients that still answer 2025-era servers through the deprecation window.

Declare the roots capability

roots in the Client constructor's capabilities tells the server it can ask for the list; listChanged: true also lets you notify it when the list changes.

import { Client } from '@modelcontextprotocol/client';

const client = new Client({ name: 'workspace-client', version: '1.0.0' }, { capabilities: { roots: { listChanged: true } } });

Declare the capability before registering the handler: without it, setRequestHandler('roots/list', …) throws.

Answer roots/list

setRequestHandler('roots/list', …) returns { roots }. Every uri must start with file://; name is optional.

const roots = [
    { uri: 'file:///home/user/projects/my-app', name: 'My App' },
    { uri: 'file:///home/user/data', name: 'Data' }
];

client.setRequestHandler('roots/list', async () => {
    return { roots };
});

A connected server that requests roots/list receives exactly what the handler returned:

[
  { uri: 'file:///home/user/projects/my-app', name: 'My App' },
  { uri: 'file:///home/user/data', name: 'Data' }
]

Roots are advisory boundaries, not an access grant — the server still reaches the filesystem with its own permissions, and the SDK never enforces the list on either side.

INFO

On a 2026-07-28 connection there is no server-to-client request channel; the same handler fulfils a roots/list request embedded in an input_required result — see Protocol versions.

Tell the server when the roots change

sendRootsListChanged() sends notifications/roots/list_changed; it requires the listChanged: true declared above.

roots.push({ uri: 'file:///home/user/projects/another-app', name: 'Another app' });
await client.sendRootsListChanged();

The notification carries no payload. A server that watches it requests roots/list again and receives the updated list:

[
  { uri: 'file:///home/user/projects/my-app', name: 'My App' },
  { uri: 'file:///home/user/data', name: 'Data' },
  {
    uri: 'file:///home/user/projects/another-app',
    name: 'Another app'
  }
]

Recap

• Roots are deprecated (SEP-2577): pass paths through tool arguments, resource URIs, or configuration instead.
• capabilities: { roots: { listChanged: true } } on the Client constructor declares the capability; register the roots/list handler only after declaring it.
• The handler returns { roots }, and every root uri starts with file://.
• Roots are advisory boundaries, not an access grant.
• sendRootsListChanged() notifies the server that the list changed; the server re-requests roots/list itself.