adk-agent-builder

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Builds ADK (Agent Development Kit) Python agents: LLM agents with tools, graph workflows of function and agent nodes, conditional routing, fan-out and join, schema-validated delegation between agents, human-in-the-loop pauses, and pytest coverage for all of it. Use when asked to create an agent or a workflow, add a tool to one, branch or loop between nodes, run steps in parallel, pause for user approval, or test an agent. Don't use for explaining how ADK works internally or designing its core components (use `adk-architecture`), for an agent that already runs but misbehaves (use `adk-debug`), for authoring a sample under `contributing/` (use `adk-sample-creator`), or for naming, typing, and formatting conventions (use `adk-style`).

5installs

Sourcegoogle/adk-python

Added on2026-09-30

NPX Install

npx skill4agent add google/adk-python adk-agent-builder

SKILL.md Content

ADK Agent Builder

Read only the reference that matches the task. Loading the whole tree costs context and buries the part that matters.

Every API below was checked against

google-adk

2.6.2. If a symbol is missing at runtime, read the source under

src/google/adk/

rather than guessing a neighbouring name.

Start here

Task	Reference
First agent, environment, `adk` CLI	getting-started.md
Which import path is the canonical one	import-paths.md
The rules that cause most runtime failures	best-practices.md

Building blocks

tool-catalog.md — function tools, MCP, OpenAPI, Google API toolsets, built-in tools, custom
```
BaseTool
```
and
```
BaseToolset
```
.
function-nodes.md — plain functions as nodes: parameter resolution, generators,
```
node_input
```
typing rules.
llm-agent-nodes.md — an
```
LlmAgent
```
used as a workflow node: output types, instruction templates,
```
output_schema
```
, auto-wrapping behavior.
task-mode.md —
```
mode='task'
```
and
```
mode='single_turn'
```
delegation with schema-validated input and output.

Graph orchestration

routing-and-conditions.md — routed edges, dict routing maps, default routes, self-loops, revision loops.
parallel-and-fanout.md — fan-out edges,
```
JoinNode
```
fan-in,
```
parallel_worker=True
```
list processing.
dynamic-nodes.md — scheduling nodes at runtime with
```
ctx.run_node()
```
and imperative workflow construction.
human-in-the-loop.md —
```
RequestInput
```
, resume behavior, resumable vs replayed sessions.
advanced-patterns.md — nested workflows, retries, custom
```
BaseNode
```
subclasses, graph validation rules.
multi-agent.md — chat-transfer hierarchies, and the deprecated
```
SequentialAgent
```
/
```
LoopAgent
```
/
```
ParallelAgent
```
shells that
```
Workflow
```
replaces.

Runtime and verification

state-and-events.md — the
```
Context
```
object,
```
Event
```
fields, and how state flows between nodes.
session-and-state.md — session services, artifacts, memory, and state key scoping.
callbacks-and-plugins.md — the six agent callbacks and app-level plugins.
testing.md —
```
pytest
```
with
```
InMemoryRunner
```
, faking a model, asserting on node output.