Agent Development Kit is a Python framework for building, evaluating, deploying, and coordinating AI agents as software applications. Developers use it to compose workflows, delegate tasks between specialized agents, manage state, and connect agents to tools while choosing supported models and deployment environments. The catalogue add-ons provide workflows for using the toolkit.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add google/adk-python --skill adk-agent-buildergit clone --depth 1 https://github.com/google/adk-pythonWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/google/adk-python/adk-agent-builder)<a href="https://agentmods.dev/skills/google/adk-python/adk-agent-builder"><img src="https://agentmods.dev/badge/skills/google/adk-python/adk-agent-builder/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/google/adk-python/adk-agent-builder"><img src="https://agentmods.dev/badge/skills/google/adk-python/adk-agent-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00177 | $0.00884 |
| Opus 5.5 | $0.00071 | $0.00354 |
| Sonnet 5.5 | $0.00035 | $0.00177 |
| Haiku 4.5 | $0.00018 | $0.00088 |
Grade A, and why
adk-agent-builder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.
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
BaseToolandBaseToolset. - function-nodes.md — plain functions as nodes:
parameter resolution, generators,
node_inputtyping rules. - llm-agent-nodes.md — an
LlmAgentused as a workflow node: output types, instruction templates,output_schema, auto-wrapping behavior. - task-mode.md —
mode='task'andmode='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,
JoinNodefan-in,parallel_worker=Truelist 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
BaseNodesubclasses, graph validation rules. - multi-agent.md — chat-transfer hierarchies, and
the deprecated
SequentialAgent/LoopAgent/ParallelAgentshells thatWorkflowreplaces.
What ships with it
17 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- references/advanced-patterns.md 8.5 KB
- references/best-practices.md 5.7 KB
- references/callbacks-and-plugins.md 5.2 KB
- references/dynamic-nodes.md 3.8 KB
- references/function-nodes.md 6.1 KB
- references/getting-started.md 8.4 KB
- references/human-in-the-loop.md 5.7 KB
- references/import-paths.md 5.9 KB
- references/llm-agent-nodes.md 5.5 KB
- references/multi-agent.md 3.9 KB
- references/parallel-and-fanout.md 4.5 KB
- references/routing-and-conditions.md 4.0 KB
- references/session-and-state.md 2.7 KB
- references/state-and-events.md 4.4 KB
- references/task-mode.md 6.1 KB
- references/testing.md 7.4 KB
- references/tool-catalog.md 6.3 KB
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 72 lines · 177 tokens per session scan A 5690ecc21fa4
adk-agent-builder is a skill published in the GitHub repository google/adk-python (21,864 stars, last pushed today), licensed Apache-2.0. It adds 177 tokens to every session and 884 once invoked, about $0.0007 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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