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Agent skill

Efficient Fable

by BuilderIO in BuilderIO/skills

A skill your agent uses when running Claude Fable on codebase-heavy or token-heavy work and the user wants Fable to orchestrate research, coding, and testing while cheaper subagents do bounded heavy…

MITAuto-check passedAgent Workflows

Install Efficient Fable

skills CLI
$ npx skills add BuilderIO/skills --skill efficient-fable -a claude-code

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

GitHub CLI
$ gh skill install BuilderIO/skills efficient-fable --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/skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/efficient-fable .claude/skills/efficient-fable && 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
efficient-fable
GitHub stars
4.5k
Token cost
~996 tokens
SKILL.md length
531 words
Files
5 (incl. assets)
Skills in repo
25
Repo updated
First seen
Licence
MIT

At a glance

A skill your agent uses when running Claude Fable on codebase-heavy or token-heavy work and the user wants Fable to orchestrate research, coding, and testing while cheaper subagents do bounded heavy…

  • Works in 5 steps: Name the expensive-token risk: large… → Split independent work into subagents… → Use cheaper models for research scans,… → …
  • Running Claude Fable on codebase-heavy
  • SKILL.md covers Where Fable Shines, Delegation Pattern, Handoff Packets and Vetting Delegated Work, plus 3 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Efficient Fable is an agent skill from BuilderIO/skills. Use when running Claude Fable on codebase-heavy or token-heavy work and the user wants Fable to orchestrate research, coding, and testing while cheaper subagents do bounded heavy lifting.

Its SKILL.md is about 1000 tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files, including assets (for example `README.md`).

It sits in Agent Workflows, covering Subagents. The licence is MIT.

When your agent uses it

  • Running Claude Fable on codebase-heavy
  • Token-heavy work and the user wants Fable to orchestrate research
  • Testing while cheaper subagents do bounded heavy lifting

Example prompts

  • “/efficient-fable”

Workflow steps

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

  1. Name the expensive-token risk: large repo search, long logs, broad docs, or
  2. Split independent work into subagents before reading everything yourself.
  3. Use cheaper models for research scans, inventory, search summaries, narrow
  4. Ask subagents for concise evidence: files, line references, commands run,
  5. Spend Fable tokens on the decision layer: compare results, resolve conflicts,

What it can do on your machine

Read from SKILL.md and the folder at commit 530d9ee. 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

    No URLs in SKILL.md.

    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

Efficient Fable loads about 996 tokens when it runs. Until then it costs about 51 tokens; SKILL.md has 531 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~51
When it runs · the whole SKILL.md, loaded when a task matches
~996

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 BuilderIO/skills at commit 530d9ee, republished under its MIT licence (© BuilderIO). 531 words, ~996 tokens.

Download SKILL.mdSave it as .claude/skills/efficient-fable/SKILL.md (or your agent's skills folder). This skill also uses 4 other files; get the full folder from GitHub.
name
efficient-fable
description
Use when running Claude Fable on codebase-heavy or token-heavy work and the user wants Fable to orchestrate research, coding, and testing while cheaper subagents do bounded heavy lifting.

Efficient Fable

Use Claude Fable as the orchestrator, architect, synthesizer, and final judge. Use cheaper subagents for token-heavy research, coding, testing, and summarization that do not require Fable's full judgment.

Where Fable Shines

Reserve Fable for:

  • Decomposing ambiguous work into clean parallel slices.
  • Architecture, product, and safety tradeoffs.
  • Reading conflicting subagent reports and deciding what matters.
  • Integrating partial implementations into one coherent plan.
  • Final review, risk assessment, and user-facing synthesis.

Delegation Pattern

  1. Name the expensive-token risk: large repo search, long logs, broad docs, or repetitive edits.
  2. Split independent work into subagents before reading everything yourself.
  3. Use cheaper models for research scans, inventory, search summaries, narrow bug hunts, browser/testing passes, test output reduction, and bounded code edits.
  4. Ask subagents for concise evidence: files, line references, commands run, diffs, uncertainties, and stop conditions they hit.
  5. Spend Fable tokens on the decision layer: compare results, resolve conflicts, choose the implementation path, and review the final patch.

Prefer parallel subagents when the slices do not depend on each other. Keep blocking or highly coupled work local.

Handoff Packets

Write delegated prompts as if the subagent has no useful chat context. Include only the context it needs:

  • The repo path and exact objective.
  • The files, packages, or surfaces in scope and anything explicitly out of scope.
  • The evidence format to return: files, line refs, commands, diffs, failures, screenshots, and uncertainty.
  • The verification commands or browser flows to run, plus what success should look like when that is knowable.
  • Stop conditions: if the code does not match the prompt, a command fails after a reasonable retry, or the task needs out-of-scope files, stop and report instead of improvising.

Vetting Delegated Work

Treat subagent reports as leads, not facts. Before using a high-impact finding, opening a PR, or telling the user the work is done, Fable should reopen the important cited files, confirm the relevant line refs or failures, and review the final diff against the task. Let lighter agents gather signal; keep truth-judgment with Fable.

Show full SKILL.md (197 more words)Show less

Common Scenarios

Treat these as soft defaults, not rigid rules:

  • Research: ask lighter agents to scan docs, prior art, APIs, and repo surfaces; Fable decides what evidence changes the plan.
  • Coding: give cheaper agents bounded edits or candidate patches; Fable owns shared-file coordination, integration, and final review.
  • Testing: have Fable suggest the validation direction and the scripts or browser checks that matter. Let lighter agents run targeted tests, browser flows, screenshots, and log reduction, then report exact commands, failures, likely causes, and whether failures look flaky, environmental, or real.
  • Debugging: use cheaper agents to cluster logs, reproduce issues, and try small fixes; Fable decides which diagnosis is most trustworthy.

If a task is tiny or the validation itself needs delicate judgment, keep it with Fable.

Diagram

Use assets/fable-orchestrator.excalidraw when a visual explanation helps.

Claims

For codebase-heavy work, it is reasonable to describe this as up to 3-5x more cost-efficient and 2-4x faster when independent research, coding, or testing slices can run in parallel. Treat those as workload-dependent estimates, not guarantees.

Good launch copy:

Make Claude Fable more efficient by using cheaper subagents for token-heavy research, coding, and testing, saving Fable for judgment, architecture, synthesis, and final review.

© BuilderIO, 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 4 other files (assets) in skills/efficient-fable of BuilderIO/skills.

  • SKILL.md
  • README.md
  • assets/fable-orchestrator-dark.png
  • assets/fable-orchestrator.excalidraw
  • assets/fable-orchestrator.png

Open the folder on GitHubat commit 530d9ee

Compare with similar skills

Efficient Fable 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.

Efficient Fable compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Efficient Fable this skillBuilderIO/skills4.5k—~996Automated safety check: PassMIT
Claude Code Agent Developmentanthropics/claude-plugins-official37k8 repos~2.8kAutomated safety check: PassApache-2.0
Subagent Driven DevelopmentAsvarox/allkaraoke26137 repos~1.2kAutomated safety check: PassNone
Dispatching Parallel Agentsultralisp/ultralisp25840 repos~1.5kAutomated safety check: PassNone
Paseo Advisor Second Opiniongetpaseo/paseo20k1 repos~756Automated safety check: PassCustom licence
Task Observerrebelytics/one-skill-to-rule-them-all3.2k1 repos~12kAutomated safety check: PassCC-BY-4.0

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Categories

Questions about Efficient Fable

What does Efficient Fable do?

A skill your agent uses when running Claude Fable on codebase-heavy or token-heavy work and the user wants Fable to orchestrate research, coding, and testing while cheaper subagents do bounded heavy…. Efficient Fable is an agent skill from BuilderIO/skills. Use when running Claude Fable on codebase-heavy or token-heavy work and the user wants Fable to orchestrate research, coding, and testing while cheaper subagents do bounded heavy lifting.

When should I use Efficient Fable?

Efficient Fable fits situations like: running Claude Fable on codebase-heavy; token-heavy work and the user wants Fable to orchestrate research; testing while cheaper subagents do bounded heavy lifting.

How do I install Efficient Fable in Claude Code?

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

How do I install Efficient Fable in Codex?

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

Can I use Efficient Fable 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/skills --skill efficient-fable -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/efficient-fable, .gemini/skills/efficient-fable, .github/skills/efficient-fable and .opencode/skills/efficient-fable in your project.

What does Efficient Fable need to run?

SKILL.md names no scripts, command-line tools or credentials: Efficient Fable is instructions for the agent only.

Does Efficient Fable access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Efficient Fable 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 Efficient Fable use?

Efficient Fable 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 Efficient Fable use?

About 996 tokens (SKILL.md is roughly 4k 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 Efficient Fable?

Skills that share tags, products or a category with Efficient Fable: Claude Code Agent Development (anthropics/claude-plugins-official, 37k stars), Subagent Driven Development (Asvarox/allkaraoke, 261 stars), Dispatching Parallel Agents (ultralisp/ultralisp, 258 stars) and Paseo Advisor Second Opinion (getpaseo/paseo, 20k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Efficient Fable?

BuilderIO (a GitHub organization) maintains it in BuilderIO/skills, which has 4,528 GitHub stars. The repository holds 25 skills in this directory. The repository was last updated on October 7, 2026.

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