Namespace Nexus\Mcp\Core\Schema

Optional annotations for the client. The client can use annotations to inform how objects are used or displayed.

Base interface for metadata with name (identifier) and title (display name) properties.

Capabilities a client may support. Known capabilities are defined here, in this schema, but this is not a closed set: any client can define its own, additional capabilities.

An opaque token used to represent a cursor for pagination.

An optionally-sized icon that can be displayed in a user interface.

Describes the MCP implementation.

Represents the contents of a _meta field, which clients and servers use to attach additional metadata to their interactions. Certain key names are reserved by MCP for protocol-level metadata; implementations MUST NOT make assumptions about values at these keys. Additionally, specific schema definitions may reserve particular names for purpose-specific metadata, as declared in those definitions. Valid keys have two segments: Prefix:

• Optional — if specified, MUST be a series of labels separated by dots (.), followed by a slash (/).
• Labels MUST start with a letter and end with a letter or digit. Interior characters may be letters, digits, or hyphens (-).
• Implementations SHOULD use reverse DNS notation (e.g., com.example/ rather than example.com/).
• Any prefix where the second label is modelcontextprotocol or mcp is reserved for MCP use. For example: io.modelcontextprotocol/, dev.mcp/, org.modelcontextprotocol.api/, and com.mcp.tools/ are all reserved. However, com.example.mcp/ is NOT reserved, as the second label is example. Name:
• Unless empty, MUST start and end with an alphanumeric character ([a-z0-9A-Z]).
• Interior characters may be alphanumeric, hyphens (-), underscores (_), or dots (.).

Common params for any notification.

A progress token, used to associate progress notifications with the original request.

A revision of the Model Context Protocol identified by its release date.

A uniquely identifying ID for a request in JSON-RPC.

Extends MetaObject with additional request-specific fields. All key naming rules from MetaObject apply.

Common params for any request.

Common result fields.

Capabilities that a server may support. Known capabilities are defined here, in this schema, but this is not a closed set: any server can define its own, additional capabilities.

The set of notification types a client may opt in to on a subscriptions/listen request. Each notification type is opt-in; the server MUST NOT send notification types the client has not explicitly requested here.

Interface for classes that can be converted to and from arrays.

Marker for a content block that can be embedded in a prompt message or tool call result. Each variant carries its own type discriminator.

Base interface to add icons property.

Marker for the params object carried by a JSON-RPC request. The heavy RequestParams base (client-to-server, with required _meta) and the standalone server-to-client params both implement it.