Atlas / Skills / builderio / /efficient-fable

/efficient-fableSAFE

skills/builderio/efficient-fable

Skills for agents

Verdict
SAFE
Grade
B
Trust score
89 /100
Version
—
Hosts
—
License
MIT
Stars
4,604
01

Overview

From the repository's own README, as read at the audited commit. Badges and raw HTML are left out.

Use Claude Fable where it is worth paying for judgment.

/efficient-fable helps a Fable-class model orchestrate codebase-heavy work without spending premium tokens on every scan, log, browser run, and bounded edit. Fable keeps the hard calls: decomposition, architecture, product tradeoffs, synthesis, risk, and final review. Lighter agents do the repeatable heavy passes.

What It Does

  • Splits large work into research, coding, and testing lanes.
  • Tells Fable to choose the strategy, validation direction, and review bar.
  • Encourages cheaper agents to scan repos, summarize docs, reduce logs, run

browser checks, and attempt bounded patches.

  • Keeps evidence flowing back to Fable as files, commands, diffs, failures, and

uncertainties.

  • Uses self-contained handoff packets so delegated agents can work without

hidden context from the orchestrator chat.

  • Reminds Fable to verify important delegated claims before relying on them.

When To Use It

Use this when the task is too broad for one expensive model pass: unfamiliar repos, long test output, multi-file changes, product/architecture ambiguity, or validation work that can run in parallel.

Skip it for tiny fixes, highly coupled edits, or judgment-sensitive debugging where delegating would create more coordination cost than it saves.

Testing Guidance

Fable should suggest the validation direction and name the scripts or browser flows that matter. Lighter agents can run those checks, collect screenshots, reduce logs, and report whether failures look real, flaky, or environmental.

The point is not to outsource responsibility. Fable still decides what signal is trustworthy.

Delegation Quality

Good handoffs

Read from source at commit 3e67e99960c8OBSERVED · 2026-10-20
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02

What it tells the agent

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
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.

## 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.
03

Trust audit

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

LayerWhat it checksResult
L0Provenance & inventoryPASS
L1Static analysis of the codeNA
L2Instruction surface (what it tells the agent)PASS
L3Class-specific surfacePASS
L4Behavioural (sandbox)SKIPPED

What the source does

Filesystem
none-observed
Network
none-observed
Shell
none-observed
Dependencies
pinned
Secrets in source
none-found

Findings (0)

No findings outside the package's declared scope.

Gates applied: no_behavioural_pass.

Audited 2026-10-20 · audit v0.4.1 · source sha 3e67e99960c8full audit observations/trust-audit/skill/builderio__efficient-fable.json · Report an issue / request a re-scan
04

Audit history

Every audit this skill has had.

DateSourceVerdictGradeScoreChange
2026-10-203e67e99960c8SAFEB89first audit
05

Questions

What does the efficient-fable — builderio/skills skill do?

Skills for agents

Is efficient-fable — builderio/skills safe to install?

The audit found nothing in the source that contradicts what it says it does, and graded it B (89/100). Grade A is held back for packages that have also passed a sandboxed behavioural run, which is why a clean skill reads B.

What can efficient-fable — builderio/skills access on my machine?

The audit observed no filesystem, network or shell use at all in its source.

How current is this page?

The grade is for one exact copy of the source (3e67e99960c8), read on 2026-10-20. The repository is watched, and a new audit runs when it changes — this is the first audit.

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