8. Capabilities

The capabilities object declares the server’s supported features as reported during MCP initialization. It is OPTIONAL.

8.1 Overview

Capabilities provide hints about the server’s feature set beyond the tools, resources, and prompts it exposes. These correspond to the capabilities returned in the MCP InitializeResult.

8.2 Properties

Property	Type	Description
`tools`	object	Tool-related capabilities
`tools.listChanged`	boolean	Whether the server sends `notifications/tools/list_changed`
`resources`	object	Resource-related capabilities
`resources.subscribe`	boolean	Whether the server supports resource subscriptions
`resources.listChanged`	boolean	Whether the server sends `notifications/resources/list_changed`
`prompts`	object	Prompt-related capabilities
`prompts.listChanged`	boolean	Whether the server sends `notifications/prompts/list_changed`
`completions`	object	Present if the server supports argument autocompletion (MCP 2025-03-26+)
`logging`	object	Present if the server supports sending log messages to the client
`tasks`	object	Present if the server supports task-augmented requests (MCP 2025-11-25+)
`experimental`	object	Experimental, non-standard capabilities

8.3 Tasks Capability

The tasks object, when present, indicates the server supports long-running task management:

Property	Type	Description
`tasks.list`	object	Server supports listing active tasks
`tasks.cancel`	object	Server supports cancelling tasks
`tasks.requests.tools.call`	object	Tool calls can be task-augmented

8.4 Extensibility

The capabilities object allows additional properties beyond those defined here. Implementations SHOULD preserve unknown capability properties when processing documents.

8.5 Example

{
  "capabilities": {
    "tools": { "listChanged": true },
    "resources": { "subscribe": true, "listChanged": true },
    "prompts": { "listChanged": false },
    "completions": {},
    "logging": {}
  }
}