Struct and module-based JSON schema generated from modelcontextprotocol.io JSON schema.

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 (.).