New: 98,000+ skills indexed from GitHub repos with 100+ stars · every skill safety-checkedBrowse top skillsTop skills
Esc to closeBrowse all skills
Submit a skillBrowse skills
Submit a skillBrowse skills

Agent skill

Harness Agents

by BuilderIO in BuilderIO/agent-native

Add or use full agent harness runtimes like Claude Code, Codex, Pi, Cursor, Mastra, or ACP agents inside Agent-Native.

No licenceAuto-check passed

Install Harness Agents

skills CLI
$ npx skills add BuilderIO/agent-native --skill harness-agents -a claude-code

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

GitHub CLI
$ gh skill install BuilderIO/agent-native harness-agents --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/BuilderIO/agent-native.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/harness-agents .claude/skills/harness-agents && 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
harness-agents
GitHub stars
7.1k
Token cost
~1.6k tokens
SKILL.md length
658 words
Files
1
Skills in repo
102
Repo updated
First seen
Licence
None found

At a glance

Add or use full agent harness runtimes like Claude Code, Codex, Pi, Cursor, Mastra, or ACP agents inside Agent-Native.

  • Works in 3 steps: Register or resolve a harness adapter. → Start a turn through the run-manager… → Persist native session state in SQL.
  • SKILL.md covers Rule, Why, How and ACP Agents, plus 5 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Harness Agents is an agent skill from BuilderIO/agent-native. Add or use full agent harness runtimes like Claude Code, Codex, Pi, Cursor, Mastra, or ACP agents inside Agent-Native.

Its SKILL.md is about 1.6k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It works with Mastra. The repository describes itself as: A framework for building agentic apps.

Example prompts

  • “/harness-agents”

Requirements

  • Docker

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

  1. Register or resolve a harness adapter.
  2. Start a turn through the run-manager bridge.
  3. Persist native session state in SQL.

What it can do on your machine

Read from SKILL.md and the folder at commit be0d784. 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 (its code samples are typescript).

    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):

    • agentclientprotocol.com

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

  • Credentials

    Names no API keys, tokens, secrets or passwords.

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

Context cost

Harness Agents loads about 1.6k tokens when it runs. Until then it costs about 33 tokens; SKILL.md has 658 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~33
When it runs · the whole SKILL.md, loaded when a task matches
~1.6k

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

Without a licence we can't republish the file, so here is its outline and opening line. It has 658 words (~1,636 tokens).

“Full agent harnesses are not AgentEngine providers. Use the AgentHarness substrate in @agent-native/core/agent/harness.”

— opening of SKILL.md by BuilderIO
name
harness-agents
scope
dev

Read the full SKILL.md on GitHub

Files

Just SKILL.md in .agents/skills/harness-agents of BuilderIO/agent-native.

Open the folder on GitHubat commit be0d784

Compare with similar skills

Harness Agents 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.

Harness Agents compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Harness Agents this skillBuilderIO/agent-native7.1k—~1.6kAutomated safety check: PassNone
Docs Auditmastra-ai/mastra29k—~3kAutomated safety check: PassCustom licence
Builder Smoke Testmastra-ai/mastra29k—~11kAutomated safety check: NotesCustom licence
Mastra Smoke Testmastra-ai/mastra29k—~4kAutomated safety check: NotesCustom licence
React Best Practicesmastra-ai/mastra29k—~1.9kAutomated safety check: PassCustom licence
Pensieve Searcharkohut/pensieve1.4k—~8.2kAutomated safety check: PassApache-2.0

Similar skills

  • Docs Audit

    mastra-ai/mastra

    Autonomous, report-only documentation review for Mastra docs.

    29k GitHub stars~3k tokensUpdated today
    Auto-check passed

  • Builder Smoke Test

    mastra-ai/mastra

    Smoke test the Agent Builder feature branch end-to-end against a hermetic project scaffolded by the skill (linked to the current worktree).

    29k GitHub stars~11k tokensUpdated today
    Testing & QAAuto-check: notes

  • Mastra Smoke Test

    mastra-ai/mastra

    Smoke test Mastra projects locally or deploy to staging/production.

    29k GitHub stars~4k tokensUpdated today
    Testing & QAAuto-check: notes

  • React Best Practices

    mastra-ai/mastra

    React performance optimization guidelines from Mastra Engineering.

    29k GitHub stars~1.9k tokensUpdated today
    Frontend & DesignAuto-check passed

  • Pensieve Search

    arkohut/pensieve

    Search the user's local Pensieve screenshot archive by text, app, or time range.

    1.4k GitHub stars~8.2k tokensUpdated 2 mo ago
    Data & AnalyticsAuto-check passed

  • Mastra

    LiorVainer/data-israel

    Comprehensive Mastra framework guide. An agent skill from LiorVainer/data-israel.

    130 GitHub starsUsed in 2 repos~1.6k tokens
    AI & LLM EngineeringAuto-check passed

More from BuilderIO/agent-native

All 102 skills in this repo

  • Actions

    BuilderIO/agent-native

    How to create and run agent actions. An agent skill from BuilderIO/agent-native.

    7.1k GitHub stars~4.4k tokensUpdated today
    Auto-check passed

  • Client Methods

    BuilderIO/agent-native

    Client method surface rules. An agent skill from BuilderIO/agent-native.

    7.1k GitHub stars~1.2k tokensUpdated today
    Auto-check passed

  • Adding A Feature

    BuilderIO/agent-native

    The four-area checklist every new feature must complete. An agent skill from BuilderIO/agent-native.

    7.1k GitHub stars~4k tokensUpdated today
    Auto-check passed

  • Address Feedback

    BuilderIO/agent-native

    Triage feedback from docs, issues, Slack threads, or pasted notes into verified bugs, UX proposals, unclear questions, and skipped noise.

    7.1k GitHub stars~4.4k tokensUpdated today
    Auto-check passed

  • Audit Log

    BuilderIO/agent-native

    Durable, access-scoped, append-only record of who changed what app data, when, and whether it was the agent or a human.

    7.1k GitHub stars~2k tokensUpdated today
    Auto-check passed

  • Automations

    BuilderIO/agent-native

    Event-triggered and schedule-triggered automations with natural-language conditions.

    7.1k GitHub stars~4.4k tokensUpdated today
    Auto-check passed

Works with

Questions about Harness Agents

What does Harness Agents do?

Add or use full agent harness runtimes like Claude Code, Codex, Pi, Cursor, Mastra, or ACP agents inside Agent-Native. Harness Agents is an agent skill from BuilderIO/agent-native. Add or use full agent harness runtimes like Claude Code, Codex, Pi, Cursor, Mastra, or ACP agents inside Agent-Native.

How do I install Harness Agents in Claude Code?

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

How do I install Harness Agents in Codex?

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

Can I use Harness Agents 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 BuilderIO/agent-native --skill harness-agents -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/harness-agents, .gemini/skills/harness-agents, .github/skills/harness-agents and .opencode/skills/harness-agents in your project.

What does Harness Agents need to run?

SKILL.md names no scripts, command-line tools or credentials: Harness Agents is instructions for the agent only. Our summary lists: Docker.

Does Harness Agents access the network?

SKILL.md names 1 domain. As links in the text: agentclientprotocol.com. This is read from the text; nothing was executed.

Is Harness Agents 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 Harness Agents use?

No licence was found for Harness Agents or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.

How many tokens does Harness Agents use?

About 1.6k tokens (SKILL.md is roughly 6.5k 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 Harness Agents?

Skills that share tags, products or a category with Harness Agents: Docs Audit (mastra-ai/mastra, 29k stars), Builder Smoke Test (mastra-ai/mastra, 29k stars), Mastra Smoke Test (mastra-ai/mastra, 29k stars) and React Best Practices (mastra-ai/mastra, 29k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Harness Agents?

BuilderIO (a GitHub organization) maintains it in BuilderIO/agent-native, which has 7,103 GitHub stars. The repository holds 102 skills in this directory. The repository was last updated on October 9, 2026.

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