a2a docs›reference›a2a_client

a2a_pack.a2a_client

Agent-to-agent invocation surface available via ctx.call(...).

An agent never speaks raw HTTP to another agent. It calls ctx.call(target, skill, args, grant=...) and the runtime-attached :class:A2AClient handles transport: HTTP for cross-pod, in-memory for local tests, anything else (gRPC, message bus) for future runtimes.

The grant token (see :mod:a2a_pack.grants) is the only way to hand workspace access across agents. Callee-side runtime validates it before materializing a :class:WorkspaceClient.

A2AClient (class)

A2AClient()

Transport-shaped agent-to-agent client.

call (method)

call(self, target: 'str', skill: 'str', *, args: 'dict[str, Any] | None' = None, grant: 'str | None' = None, timeout: 'float | None' = None) -> 'CallResult'

Invoke skill on target and return its :class:CallResult.

target is opaque to this layer — for the HTTP impl it's an agent URL; for the in-memory impl it's an agent name.

CallResult (class)

CallResult(result: 'Any', events: 'tuple[dict[str, Any], ...]' = (), artifacts: 'tuple[dict[str, Any], ...]' = (), grant_id: 'str | None' = None) -> None

What an A2A invocation returns to the calling skill.

__init__ (method)

__init__(self, result: 'Any', events: 'tuple[dict[str, Any], ...]' = (), artifacts: 'tuple[dict[str, Any], ...]' = (), grant_id: 'str | None' = None) -> None

Initialize self. See help(type(self)) for accurate signature.

HttpA2AClient (class)

HttpA2AClient(default_timeout: 'float' = 60.0) -> None

A2A client that POSTs to the standard /invoke/{skill} endpoint.

__init__ (method)

__init__(self, default_timeout: 'float' = 60.0) -> None

Initialize self. See help(type(self)) for accurate signature.

call (method)

call(self, target: 'str', skill: 'str', *, args: 'dict[str, Any] | None' = None, grant: 'str | None' = None, timeout: 'float | None' = None) -> 'CallResult'

Invoke skill on target and return its :class:CallResult.

target is opaque to this layer — for the HTTP impl it's an agent URL; for the in-memory impl it's an agent name.

InMemoryA2AClient (class)

InMemoryA2AClient(agents: "dict[str, 'A2AAgent']", ctx_factory: 'Any' = None) -> None

Routes calls to agent instances registered by name.

The receiving agent gets a new :class:RunContext built by the ctx_factory callable, so caller and callee don't share state. Pass ctx_factory=lambda agent, grant: ... to control how scoped workspaces / sandboxes are wired in.

__init__ (method)

__init__(self, agents: "dict[str, 'A2AAgent']", ctx_factory: 'Any' = None) -> None

Initialize self. See help(type(self)) for accurate signature.

call (method)

call(self, target: 'str', skill: 'str', *, args: 'dict[str, Any] | None' = None, grant: 'str | None' = None, timeout: 'float | None' = None) -> 'CallResult'

Invoke skill on target and return its :class:CallResult.

target is opaque to this layer — for the HTTP impl it's an agent URL; for the in-memory impl it's an agent name.

Source: apps/a2a/a2a_pack/a2a_client.py