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Agent skill

Agent SDK Builder

by OpenHands in OpenHands/extensions

Guided workflow for building custom AI agents using the OpenHands Software Agent SDK.

MITAuto-check passedAI & LLM Engineering

Install Agent SDK Builder

skills CLI
$ npx skills add OpenHands/extensions --skill agent-sdk-builder -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install OpenHands/extensions agent-sdk-builder --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/agent-sdk-builder .claude/skills/agent-sdk-builder && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
agent-sdk-builder
GitHub stars
158
Token cost
~713 tokens
SKILL.md length
358 words
Files
6
Skills in repo
78
Repo updated
First seen
Licence
MIT

At a glance

Guided workflow for building custom AI agents using the OpenHands Software Agent SDK.

  • You want to create a new agent through an interactive interview process that gathers requirements and generates implementation plans
  • Needs LLM_API_KEY
  • Tasks that involve Building AI agents
  • Tasks that involve Planning

What it does

Agent SDK Builder is an agent skill from OpenHands/extensions. Guided workflow for building custom AI agents using the OpenHands Software Agent SDK. Use when you want to create a new agent through an interactive interview process that gathers requirements and generates implementation plans.

Its SKILL.md is about 710 tokens, which your agent loads only when the skill is triggered. The skill folder holds 7 other files (for example `.plugin/plugin.json`, `README.md` and `commands/agent-builder.md`).

It sits in AI & LLM Engineering, covering Building AI agents and Planning. The repository describes itself as: Public registry for OpenHands extensions. The licence is MIT.

When your agent uses it

  • You want to create a new agent through an interactive interview process that gathers requirements and generates implementation plans
  • Tasks that involve Building AI agents
  • Tasks that involve Planning

Example prompts

  • “/agent-sdk-builder”

Requirements

  • Python 3
  • A credential in LLM_API_KEY

What it can do on your machine

Read from SKILL.md and the folder at commit d008b81. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Links to these hosts (documentation or services it may open):

    • github.com
    • docs.openhands.dev

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names these keys or tokens, usually read from environment variables:

    • LLM_API_KEY

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Agent SDK Builder loads about 713 tokens when it runs. Until then it costs about 62 tokens; SKILL.md has 358 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~62
When it runs · the whole SKILL.md, loaded when a task matches
~713

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from OpenHands/extensions at commit d008b81, republished under its MIT licence (© OpenHands). 358 words, ~713 tokens.

Download SKILL.mdSave it as .claude/skills/agent-sdk-builder/SKILL.md (or your agent's skills folder). This skill also uses 5 other files; get the full folder from GitHub.
name
agent-sdk-builder
description
Guided workflow for building custom AI agents using the OpenHands Software Agent SDK. Use when you want to create a new agent through an interactive interview process that gathers requirements and generates implementation plans.
triggers
/agent-builder

Agent Builder and Interviewer Role

You are an expert requirements gatherer and agent builder. You must progressively interview the user to understand what type of agent they are looking to build. You should ask one question at a time when interviewing to avoid overwhelming the user.

Please refer to the user's initial promot: {INITIAL_PROMPT}

If {INITIAL_PROMPT} is blank, your first interview question should be: "Please provide a brief description of the type of agent you are looking to build."

Understanding the OpenHands Software Agent SDK

At the end of the interview, respond with a summary of the requirements. Then, proceed to thoroughly understand how the OpenHands Software Agent SDK works, it's various APIs, and examples. To do this:

After analyzing the OpenHands Agent SDK, you may optionally ask additional clarifying questions in case it's important for the technical design of the agent.

Show full SKILL.md (178 more words)Show less

Generating the SDK Plan

You can then proceed to build a technical implementation plan based on the user requirements and your understanding of how the OpenHands Agent SDK works.

  • The plan should be stored in "plan/SDK_PLAN.md" from the root of the workspace.
  • A visual representation of how the agent should work based on the SDK_PLAN.md. This should look like a flow diagram with nodes and edges. This should be generated using Javascript, HTML, and CSS and then be rendered using the built-in web server. Store this in the plan/ directory.

Implementing the Plan

After the plan is generated, please ask the user if they are ready to generate the SDK implementation. When they approve, please make sure the code is stored in the "output/" directory. Make sure the code provides logging that a user can see in the terminal. Ideally, the SDK is a single python file.

Additional guidelines:

  • Users can configure their LLM API Key using an environment variable named "LLM_API_KEY"
  • Unless otherwise specified, default to this model: openhands/claude-sonnet-4-5-20250929. This is configurable through the LLM_BASE_MODEL environment variable.

© OpenHands, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 5 other files in skills/agent-sdk-builder of OpenHands/extensions.

  • SKILL.md
  • .claude-plugin
  • .codex-plugin
  • .plugin/plugin.json
  • README.md
  • commands/agent-builder.md

Open the folder on GitHubat commit d008b81

Compare with similar skills

Agent SDK Builder next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Agent SDK Builder compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Agent SDK Builder this skillOpenHands/extensions158—~713Automated safety check: PassMIT
Pydantic AI Harnesspydantic/pydantic-ai20k—~4.9kAutomated safety check: PassMIT
Claude Code Clawdbotwin4r/claude-code-clawdbot-skill123—~2.5kAutomated safety check: WarnNone
Agent BuildershareAI-lab/learn-claude-code78k6 repos~1.2kAutomated safety check: PassMIT
Planning With Filesjarrodwatts/claude-code-config1.1k5 repos~967Automated safety check: PassNone
Agenticx Agent BuilderDemonDamon/AgenticX294—~893Automated safety check: PassApache-2.0

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Categories

Questions about Agent SDK Builder

What does Agent SDK Builder do?

Guided workflow for building custom AI agents using the OpenHands Software Agent SDK. Agent SDK Builder is an agent skill from OpenHands/extensions. Guided workflow for building custom AI agents using the OpenHands Software Agent SDK.

When should I use Agent SDK Builder?

Agent SDK Builder fits situations like: you want to create a new agent through an interactive interview process that gathers requirements and generates implementation plans; tasks that involve Building AI agents; tasks that involve Planning.

How do I install Agent SDK Builder in Claude Code?

Run `npx skills add OpenHands/extensions --skill agent-sdk-builder -a claude-code`. Or copy the skill folder (skills/agent-sdk-builder in OpenHands/extensions) into .claude/skills/agent-sdk-builder in your project. Claude Code loads it when a task matches its description.

How do I install Agent SDK Builder in Codex?

Run `npx skills add OpenHands/extensions --skill agent-sdk-builder -a codex`. Or copy the skill folder (skills/agent-sdk-builder in OpenHands/extensions) into .agents/skills/agent-sdk-builder in your project. Codex loads it when a task matches its description.

Can I use Agent SDK Builder in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add OpenHands/extensions --skill agent-sdk-builder -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/agent-sdk-builder, .gemini/skills/agent-sdk-builder, .github/skills/agent-sdk-builder and .opencode/skills/agent-sdk-builder in your project.

What does Agent SDK Builder need to run?

Going by SKILL.md and its folder, Agent SDK Builder needs credentials named LLM_API_KEY. Our summary lists: Python 3; A credential in LLM_API_KEY.

Does Agent SDK Builder access the network?

SKILL.md names 2 domains. As links in the text: github.com and docs.openhands.dev. This is read from the text; nothing was executed.

Is Agent SDK Builder safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Agent SDK Builder use?

Agent SDK Builder is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Agent SDK Builder use?

About 713 tokens (SKILL.md is roughly 2.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Agent SDK Builder?

Skills that share tags, products or a category with Agent SDK Builder: Pydantic AI Harness (pydantic/pydantic-ai, 20k stars), Claude Code Clawdbot (win4r/claude-code-clawdbot-skill, 123 stars), Agent Builder (shareAI-lab/learn-claude-code, 78k stars) and Planning With Files (jarrodwatts/claude-code-config, 1.1k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Agent SDK Builder?

OpenHands (a GitHub organization) maintains it in OpenHands/extensions, which has 158 GitHub stars. The repository holds 78 skills in this directory. The repository was last updated on October 7, 2026.

Source: OpenHands/extensions on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.