Module types 

All A2A protocol wire types.

Modules

agent_card

Agent card and capability discovery types.

artifact

Artifact types for the A2A protocol.

error

A2A protocol error types.

events

Server-sent event types for A2A streaming.

extensions

Agent extension and card-signature types.

jsonrpc

JSON-RPC 2.0 envelope types.

message

Message types for the A2A protocol.

params

JSON-RPC method parameter types.

push

Push notification configuration types.

responses

RPC method response types.

security

Security scheme types for A2A agent authentication.

signing

Agent card signing and verification (spec §10).

task

Task types for the A2A protocol.

Structs

A2aError

The canonical error type for A2A protocol operations.

AgentCapabilities

Optional capability flags advertised by an agent.

AgentCard

The root discovery document for an A2A agent.

AgentCardSignature

A cryptographic signature over an crate::agent_card::AgentCard.

AgentExtension

Describes an optional extension that an agent supports.

AgentInterface

A transport interface offered by an agent.

AgentProvider

The organization that operates or publishes the agent.

AgentSkill

A discrete capability offered by an agent.

ApiKeySecurityScheme

API key security scheme: a token sent in a header, query parameter, or cookie.

Artifact

An output artifact produced by an agent.

ArtifactId

Opaque unique identifier for an Artifact.

AuthenticationInfo

Authentication information used by an agent when calling a push webhook.

AuthorizationCodeFlow

OAuth 2.0 authorization code flow.

CancelTaskParams

Parameters for the CancelTask method.

ClientCredentialsFlow

OAuth 2.0 client credentials flow.

ContextId

Opaque unique identifier for a conversation context.

DeletePushConfigParams

Parameters for the DeleteTaskPushNotificationConfig method.

DeviceCodeFlow

OAuth 2.0 device authorization flow (RFC 8628).

GetExtendedAgentCardParams

Parameters for the GetExtendedAgentCard method.

GetPushConfigParams

Parameters for the GetTaskPushNotificationConfig method.

HttpAuthSecurityScheme

HTTP authentication security scheme (Bearer, Basic, etc.).

ImplicitFlow

OAuth 2.0 implicit flow (deprecated; retained for compatibility).

JsonRpcError

The error object within a JSON-RPC 2.0 error response.

JsonRpcErrorResponse

An error JSON-RPC 2.0 response.

JsonRpcRequest

A JSON-RPC 2.0 request object.

JsonRpcSuccessResponse

A successful JSON-RPC 2.0 response.

JsonRpcVersion

The JSON-RPC protocol version marker.

ListPushConfigsParams

Parameters for the ListTaskPushNotificationConfigs method.

ListPushConfigsResponse

The result of a ListTaskPushNotificationConfigs call.

ListTasksParams

Parameters for the ListTasks method.

Message

A message exchanged between a client and an agent.

MessageId

Opaque unique identifier for a Message.

MessageSendParams

Parameters for the SendMessage and SendStreamingMessage methods.

MutualTlsSecurityScheme

Mutual TLS security scheme.

OAuth2SecurityScheme

OAuth 2.0 security scheme.

OAuthFlows

Available OAuth 2.0 flows for an OAuth2SecurityScheme.

OpenIdConnectSecurityScheme

OpenID Connect security scheme.

Part

A content part within a Message or crate::artifact::Artifact.

PasswordOAuthFlow

OAuth 2.0 resource owner password credentials flow (deprecated but in spec).

SecurityRequirement

A security requirement object mapping scheme names to their required scopes.

SendMessageConfiguration

Optional configuration for a SendMessage or SendStreamingMessage call.

StringList

A list of strings used within a SecurityRequirement map value.

Task

A unit of work managed by an A2A agent.

TaskArtifactUpdateEvent

A streaming event that delivers a new or updated artifact.

TaskId

Opaque unique identifier for a Task.

TaskIdParams

Minimal parameters identifying a single task by ID.

TaskListResponse

The result of a ListTasks call: a page of tasks with pagination.

TaskPushNotificationConfig

Configuration for delivering task updates to a webhook endpoint.

TaskQueryParams

Parameters for the GetTask method.

TaskStatus

The current status of a Task, combining state with an optional message and timestamp.

TaskStatusUpdateEvent

A streaming event that reports a change in task state.

TaskVersion

Monotonically increasing version counter for optimistic concurrency control.

Enums

ApiKeyLocation

Where an API key is placed in the request.

ErrorCode

Numeric error codes defined by JSON-RPC 2.0 and the A2A v1.0 specification.

JsonRpcResponse

A JSON-RPC 2.0 response: either a success with a result or an error with an error object.

MessageRole

The originator of a Message.

PartContent

The content of a Part, discriminated by field presence (proto oneof).

SecurityScheme

A security scheme supported by an agent, discriminated by the "type" field.

SendMessageResponse

The result of a SendMessage call: either a completed Task or an immediate Message response.

StreamResponse

A single event payload in an A2A streaming response.

TaskState

The lifecycle state of a Task.

Constants

A2A_CONTENT_TYPE

A2A-specific content type for JSON payloads.

A2A_VERSION

A2A protocol version string.

A2A_VERSION_HEADER

HTTP header name for the A2A protocol version.

Functions

utc_now_iso8601

Returns the current UTC time as an ISO 8601 string (e.g. "2026-03-15T12:00:00Z").

Type Aliases

A2aResult

Convenience type alias: Result<T, A2aError>.

AuthenticatedExtendedCardResponse

The full (private) agent card returned by agent/authenticatedExtendedCard.

JsonRpcId

A JSON-RPC 2.0 request/response identifier.

NamedSecuritySchemes

A map from security scheme name to its definition, as used in AgentCard.securitySchemes.