a2a.utils.input_mode_validator module

Shared policy for checking message parts against an agent’s declared input modes.

a2a.utils.input_mode_validator.validate_input_modes(message: Message, agent_card: AgentCard) → None

Rejects parts whose media type the agent card does not declare.

The allowed set is the union of default_input_modes and every skill’s input_modes, which may widen it: a skill’s input_modes overrides the card default for that skill. A request does not name the skill that will serve it, so the union is the most that can be decided here – anything outside it is supported by no skill and cannot be served, while a media type inside it may still reach a skill that does not take it, which only that skill can answer.

A card declaring no input modes anywhere accepts everything: an empty union is an absent declaration, not an empty allowlist. media_type is a proto3 string, so a part that omits it arrives as ‘’ and is likewise not checked – only a media type the client actually stated can contradict the card.