uf-useful-for

name	uf - Useful For
description	Given a skill or method, map its best-fit use cases, failure conditions, limits, and alternative skills with explicit switch conditions.
output	{"format":"prose"}

UF - Useful For

Input: $ARGUMENTS

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Core Principles

1. Every tool has a sweet spot. A skill that's excellent for one situation is mediocre for another. The sweet spot isn't "what it can do" — it's "what it does BETTER than alternatives."

2. Failure cases are more useful than success cases. Knowing when a skill works is helpful. Knowing when it FAILS is essential — it prevents wasted effort and wrong-tool choices.

3. Alternatives exist for every skill. No skill is the only option. For every use case, there are 2-3 alternative skills that could work. The switch condition — "use X instead when Y" — is the most actionable output.

4. Limits are not failures. A skill that handles 3-person decisions but not 30-person decisions isn't failing — it has a scope limit. Limits define the boundary of appropriate use.

5. Use cases are typed. "Useful for decisions" is too vague. WHAT KIND of decisions? Binary vs multi-option, reversible vs irreversible, urgent vs deliberate. Specificity makes the mapping actionable.

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Phase 1: Target Identification

[U1] TARGET: [skill id or method name]
[U2] DESCRIPTION: [what this skill/method does — from SKILL.md or user description]
[U3] CORE_FUNCTION: [the ONE thing this skill does better than anything else]
[U4] INPUT_TYPE: [what it takes as input]
[U5] OUTPUT_TYPE: [what it produces]

If the target is a skill: read its SKILL.md to understand its actual mechanics. If the target is a method/framework: describe its core operation.

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Phase 2: Best-Fit Use Cases

Map the situations where this skill is the RIGHT choice:

[U-N] USE_CASE: [specific situation]
  WHY_THIS_SKILL: [what makes this skill better than alternatives for this case]
  EXAMPLE: [concrete example of this use case]
  FIT: [excellent | good]

Use Case Dimensions

For each use case, specify:

• Input type: What kind of input makes this skill shine
• Complexity: Simple vs complex problems
• Urgency: Quick decisions vs deep deliberation
• Certainty: How much is known when invoked
• Scale: Small vs large scope

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Phase 3: Failure Cases and Limits

Failure Cases (skill produces bad output)

[U-N] FAILURE: [situation where this skill fails]
  WHY_FAILS: [what about this situation breaks the skill's assumptions]
  SIGNAL: [how you'd know you're in a failure case]
  INSTEAD: /[alternative-id] — [why the alternative works here]

Limits (skill works but suboptimally)

[U-N] LIMIT: [boundary of effective use]
  WHAT_HAPPENS: [how performance degrades past this limit]
  THRESHOLD: [where approximately the limit is]
  WORKAROUND: [how to extend past the limit, if possible]

Anti-Patterns (common misuses)

[U-N] ANTI_PATTERN: [common wrong application]
  WHY_TEMPTING: [why people try this]
  WHY_WRONG: [why it doesn't work]
  INSTEAD: /[alternative-id]

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Phase 4: Alternative Mapping

For each use case, identify what ELSE could work:

[U-N] ALTERNATIVE: /[skill-id] — [name]
  OVERLAPS_ON: [which use cases both skills handle]
  USE_THIS_WHEN: [specific condition favoring the target skill]
  USE_ALTERNATIVE_WHEN: [specific condition favoring the alternative]
  KEY_DIFFERENCE: [the fundamental distinction]

Switch Conditions

The most actionable output — explicit "if X then use Y":

[U-N] SWITCH CONDITIONS:
  USE /target WHEN: [condition 1], [condition 2]
  USE /alt-1 INSTEAD WHEN: [condition]
  USE /alt-2 INSTEAD WHEN: [condition]
  USE /alt-3 INSTEAD WHEN: [condition]

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Phase 5: Output

USEFUL FOR
==========

TARGET: /[id] — [name]
CORE FUNCTION: [one sentence]

BEST FIT (use this skill when):
  1. [use case] — WHY: [what makes this the right choice]
  2. [use case] — WHY: [reason]
  3. [use case] — WHY: [reason]

FAILURE CASES (don't use when):
  1. [situation] — USE INSTEAD: /[alt] — WHY: [reason]
  2. [situation] — USE INSTEAD: /[alt] — WHY: [reason]

LIMITS:
  1. [limit] — DEGRADES AT: [threshold]
  2. [limit] — DEGRADES AT: [threshold]

SWITCH CONDITIONS:
  USE /target WHEN: [conditions]
  USE /alt-1 INSTEAD WHEN: [condition]
  USE /alt-2 INSTEAD WHEN: [condition]

ANTI-PATTERNS:
  1. [common misuse] — USE INSTEAD: /[alt]

READY FOR:
- /cmp /target vs /alt — to compare specific alternatives
- /dtse [function] — to find other skills in this space

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Failure Modes

Failure	Signal	Fix
Only success cases	No failure cases or limits listed	Every skill has failure cases. Find at least 2
Vague use cases	"Good for decisions" without specificity	Which kind of decisions? Under what conditions?
No alternatives	Skill presented as the only option	Every skill has 2-3 alternatives. Find them
No switch conditions	Alternatives listed without "when to switch"	The whole point is knowing WHEN to use each
Title-based analysis	Assessment based on skill name, not actual SKILL.md content	Read the actual skill before mapping
All positive	No anti-patterns or limits identified	Users misuse every skill. Find the common misuses

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Depth Scaling

Depth	Min Use Cases	Min Failure Cases	Min Alternatives	Switch Conditions
1x	3	1	2	1
2x	5	3	3	3
4x	8	5	5	5
8x	12	8	8	All pairs

Default: 2x. These are floors.

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Pre-Completion Checklist

• Target skill read/understood (not just named)
• Core function stated in one sentence
• Best-fit use cases are specific (not "good for analysis")
• Failure cases identified with alternative routing
• Limits specified with thresholds
• Anti-patterns identified (common misuses)
• Alternatives mapped with explicit switch conditions
• Switch conditions are actionable ("when X, use Y")

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Integration

• Use from: /dtse (after finding a skill, understand its applicability)
• Complementary: /cmp (compare specific alternatives in depth)
• Complementary: /dtse (find a skill, then /uf to understand it)
• Differs from /dtse: dtse finds skills; uf analyzes a specific skill's applicability
• Differs from /cmp: cmp compares options; uf maps one skill's full territory