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Agent skill

Library Advisor

by ArabelaTso in ArabelaTso/Skills-4-SE

Recommend relevant Isabelle/HOL or Coq standard library theories, lemmas, and tactics based on proof goals.

Apache-2.0Auto-check passed

Install Library Advisor

skills CLI
$ npx skills add ArabelaTso/Skills-4-SE --skill library-advisor -a claude-code

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

GitHub CLI
$ gh skill install ArabelaTso/Skills-4-SE library-advisor --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/ArabelaTso/Skills-4-SE.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/library-for-proof-advisor .claude/skills/library-advisor && 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
library-advisor
GitHub stars
253
Token cost
~1.8k tokens
SKILL.md length
559 words
Files
4 (incl. references)
Skills in repo
150
Repo updated
First seen
Licence
Apache-2.0

At a glance

Recommend relevant Isabelle/HOL or Coq standard library theories, lemmas, and tactics based on proof goals.

  • Works in 6 steps: Analyze the Proof Goal → Determine Target System → Identify Relevant Libraries → …
  • Users need library lemmas for their proof
  • SKILL.md covers Workflow, Domain-Specific Recommendations, Recommendation Patterns and Search Strategies, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Library Advisor is an agent skill from ArabelaTso/Skills-4-SE. Recommend relevant Isabelle/HOL or Coq standard library theories, lemmas, and tactics based on proof goals. Use when: (1) Users need library lemmas for their proof, (2) Proof goals match standard library patterns, (3) Users ask what libraries to import, (4) Specific lemmas are needed for list/set/arithmetic operations, (5) Users are stuck and need to know what library support exists, or (6) Guidance on findtheorems/Search commands is needed. Supports both Isabelle/HOL and Coq standard libraries.

Its SKILL.md is about 1.8k tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files, including reference files (for example `references/coq_library.md`, `references/examples.md` and `references/isabelle_library.md`).

The repository describes itself as: A curated list of 180+ useful Claude Skills for Software Engineering and resources for customizing AI for SE workflows. The licence is Apache-2.0.

When your agent uses it

  • Users need library lemmas for their proof
  • Proof goals match standard library patterns
  • Users ask what libraries to import
  • Specific lemmas are needed for list/set/arithmetic operations

Example prompts

  • “/library-advisor”

Workflow steps

6 steps, taken from the step headings in SKILL.md.

  1. Analyze the Proof Goal
  2. Determine Target System
  3. Identify Relevant Libraries
  4. Search for Specific Lemmas
  5. Recommend Usage
  6. Suggest Search Commands

What it can do on your machine

Read from SKILL.md and the folder at commit 4f38503. 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 coq and isabelle).

    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

Library Advisor loads about 1.8k tokens when it runs, and up to ~7.3k if it reads all its reference files. Until then it costs about 129 tokens; SKILL.md has 559 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~129
When it runs · the whole SKILL.md, loaded when a task matches
~1.8k
With references · SKILL.md plus every file in references/, read only if the agent opens them
~7.3k

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 ArabelaTso/Skills-4-SE at commit 4f38503, republished under its Apache-2.0 licence (© ArabelaTso). 559 words, ~1,816 tokens.

Download SKILL.mdSave it as .claude/skills/library-advisor/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.
name
library-advisor
description
Recommend relevant Isabelle/HOL or Coq standard library theories, lemmas, and tactics based on proof goals. Use when: (1) Users need library lemmas for their proof, (2) Proof goals match standard library patterns, (3) Users ask what libraries to import, (4) Specific lemmas are needed for list/set/arithmetic operations, (5) Users are stuck and need to know what library support exists, or (6) Guidance on find_theorems/Search commands is needed. Supports both Isabelle/HOL and Coq standard libraries.

Library Usage Advisor

Recommend relevant libraries, lemmas, and theories from Isabelle/HOL or Coq standard libraries based on proof goals.

Workflow

1. Analyze the Proof Goal

Examine the goal to identify:

  • Domain: Lists, sets, arithmetic, logic, etc.
  • Operations: Specific functions or operators involved
  • Pattern: Commutativity, associativity, distributivity, etc.
  • Complexity: Simple property vs. complex relationship
2. Determine Target System

Identify which proof assistant:

  • Isabelle/HOL: Use Main library and extensions
  • Coq: Use standard library (List, Arith, etc.)
  • Both: Provide recommendations for both systems
3. Identify Relevant Libraries

Based on the domain, recommend appropriate libraries:

For list operations:

  • Isabelle: Main (List theory included)
  • Coq: Require Import List. Import ListNotations.

For arithmetic:

  • Isabelle: Main (Nat theory included)
  • Coq: Require Import Arith Lia.

For sets:

  • Isabelle: Main (Set theory included)
  • Coq: Require Import MSets.

For logic:

  • Isabelle: HOL (automatically available)
  • Coq: Require Import Logic.
4. Search for Specific Lemmas

Look for lemmas that directly match the goal:

Exact matches: Lemmas that prove the goal directly Component lemmas: Lemmas for parts of the goal Related lemmas: Similar properties that might help

Use the library reference files:

5. Recommend Usage

Provide concrete recommendations:

Direct application:

isabelle
lemma "goal"
  by (simp add: relevant_lemma)

With additional steps:

coq
Lemma goal : statement.
Proof.
  apply relevant_lemma.
  (* additional steps *)
Qed.

Manual proof with lemmas: Show how to use lemmas in a structured proof

6. Suggest Search Commands

Teach users how to find lemmas themselves:

Isabelle:

isabelle
find_theorems "pattern"
find_theorems name: "keyword"
sledgehammer

Coq:

coq
Search pattern.
Search "keyword".
Locate "notation".

Domain-Specific Recommendations

Lists

Common goals:

  • Length properties: length_append, length_rev, length_map
  • Reverse properties: rev_rev_ident, rev_append
  • Append properties: append_assoc, append_Nil
  • Map properties: map_append, map_map
  • Membership: in_set_member, set_append

Libraries:

  • Isabelle: Main (automatic)
  • Coq: List library
Arithmetic

Common goals:

  • Commutativity: add_commute, mult_commute
  • Associativity: add_assoc, mult_assoc
  • Distributivity: add_mult_distrib
  • Inequalities: Use arith/lia tactics

Libraries:

  • Isabelle: Main (Nat theory)
  • Coq: Arith, Lia, Nia
Sets

Common goals:

  • Union/intersection: Un_commute, Int_commute
  • Subset: subset_refl, subset_trans
  • Membership: Un_iff, Int_iff

Libraries:

  • Isabelle: Main (Set theory)
  • Coq: MSets or custom definitions
Logic

Common goals:

  • Conjunction: conjI, conjE
  • Disjunction: disjI1, disjI2
  • Implication: impI, mp
  • Quantifiers: allI, exI

Libraries:

  • Isabelle: HOL (automatic)
  • Coq: Logic (mostly automatic)

Recommendation Patterns

Pattern 1: Exact Lemma Match

When goal exactly matches a known lemma:

Isabelle:

isabelle
lemma "rev (rev xs) = xs"
  by (simp add: rev_rev_ident)

Coq:

coq
Lemma example : forall l, rev (rev l) = l.
Proof.
  apply rev_involutive.
Qed.
Show full SKILL.md (218 more words)Show less
Pattern 2: Combination of Lemmas

When goal needs multiple lemmas:

Isabelle:

isabelle
lemma "length (rev (xs @ ys)) = length xs + length ys"
  by (simp add: length_rev length_append)

Coq:

coq
Lemma example : forall l1 l2,
  length (rev (l1 ++ l2)) = length l1 + length l2.
Proof.
  intros.
  rewrite rev_length.
  rewrite app_length.
  reflexivity.
Qed.
Pattern 3: Automation

When goal is provable by automation:

Isabelle:

isabelle
lemma "n + m = m + n"
  by simp
(* Or: by auto, by arith *)

Coq:

coq
Lemma example : forall n m, n + m = m + n.
Proof.
  intros. lia.
Qed.
Pattern 4: Induction with Lemmas

When manual proof needed but lemmas help:

Isabelle:

isabelle
lemma "property xs"
proof (induction xs)
  case Nil
  show ?case by simp
next
  case (Cons x xs)
  show ?case using Cons.IH by (simp add: helper_lemma)
qed

Coq:

coq
Lemma example : forall l, property l.
Proof.
  induction l as [| x xs IHxs].
  - simpl. reflexivity.
  - simpl. rewrite IHxs. apply helper_lemma.
Qed.

Search Strategies

Isabelle:

isabelle
find_theorems "rev (rev _) = _"
find_theorems "length (_ @ _)"
find_theorems "_ + _ = _ + _"

Coq:

coq
Search rev.
Search (_ ++ _).
Search (?x + ?y = ?y + ?x).

Isabelle:

isabelle
find_theorems name: "append"
find_theorems name: "comm"

Coq:

coq
Search "append".
Search "comm" (_ + _).

Coq:

coq
Search (list _ -> nat).
Search (_ -> _ -> _ + _).
Strategy 4: Sledgehammer/Auto

Isabelle:

isabelle
lemma "goal"
  sledgehammer
  (* Suggests relevant lemmas and tactics *)

Coq:

coq
Lemma goal : statement.
Proof.
  auto.  (* Try automatic tactics *)
Qed.

Common Recommendations by Goal Type

"rev (rev xs) = xs"
  • Isabelle: rev_rev_ident or by simp
  • Coq: rev_involutive
"length (xs @ ys) = length xs + length ys"
  • Isabelle: length_append or by simp
  • Coq: app_length
"n + m = m + n"
  • Isabelle: add_commute or by simp
  • Coq: plus_comm or lia
"x ∈ set (xs @ ys) ⟷ x ∈ set xs ∨ x ∈ set ys"
  • Isabelle: set_append
  • Coq: in_app_iff
"map f (xs @ ys) = map f xs @ map f ys"
  • Isabelle: map_append
  • Coq: map_app

Examples

For complete examples with specific proof goals and library recommendations, see examples.md.

Tips

  • Search first: Use find_theorems/Search before proving manually
  • Check automation: Try simp/auto/lia before complex proofs
  • Use sledgehammer: In Isabelle, sledgehammer finds relevant lemmas
  • Import early: Import all needed libraries at the start
  • Learn patterns: Common properties (commutativity, etc.) have standard names
  • Read library docs: Browse standard library documentation
  • Build intuition: Learn which libraries contain which lemmas
  • Combine lemmas: Complex goals often need multiple lemmas
  • Simplify first: Use simp/simpl to reduce goals before searching

© ArabelaTso, Apache-2.0. 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 3 other files (references) in skills/library-for-proof-advisor of ArabelaTso/Skills-4-SE.

  • SKILL.md
  • references/coq_library.md
  • references/examples.md
  • references/isabelle_library.md

Open the folder on GitHubat commit 4f38503

Compare with similar skills

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Java Coding Standardsaffaan-m/ECC275k1 repos~2.9kAutomated safety check: PassMIT
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Questions about Library Advisor

What does Library Advisor do?

Recommend relevant Isabelle/HOL or Coq standard library theories, lemmas, and tactics based on proof goals. Library Advisor is an agent skill from ArabelaTso/Skills-4-SE. Recommend relevant Isabelle/HOL or Coq standard library theories, lemmas, and tactics based on proof goals.

When should I use Library Advisor?

Library Advisor fits situations like: users need library lemmas for their proof; proof goals match standard library patterns; users ask what libraries to import; specific lemmas are needed for list/set/arithmetic operations.

How do I install Library Advisor in Claude Code?

Run `npx skills add ArabelaTso/Skills-4-SE --skill library-advisor -a claude-code`. Or copy the skill folder (skills/library-for-proof-advisor in ArabelaTso/Skills-4-SE) into .claude/skills/library-advisor in your project. Claude Code loads it when a task matches its description.

How do I install Library Advisor in Codex?

Run `npx skills add ArabelaTso/Skills-4-SE --skill library-advisor -a codex`. Or copy the skill folder (skills/library-for-proof-advisor in ArabelaTso/Skills-4-SE) into .agents/skills/library-advisor in your project. Codex loads it when a task matches its description.

Can I use Library Advisor 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 ArabelaTso/Skills-4-SE --skill library-advisor -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/library-advisor, .gemini/skills/library-advisor, .github/skills/library-advisor and .opencode/skills/library-advisor in your project.

What does Library Advisor need to run?

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

Does Library Advisor 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 Library Advisor 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 Library Advisor use?

Library Advisor is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Library Advisor use?

About 1.8k tokens (SKILL.md is roughly 7.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 5.4k tokens, read only when the agent opens those files.

What are the alternatives to Library Advisor?

Skills that share tags, products or a category with Library Advisor: Telemetry Standards (supabase/supabase, 111k stars), Cpp Coding Standards (affaan-m/ECC, 275k stars), Java Coding Standards (affaan-m/ECC, 275k stars) and Advisor Mode (cursor/plugins, 10k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Library Advisor?

ArabelaTso (a GitHub user) maintains it in ArabelaTso/Skills-4-SE, which has 253 GitHub stars. The repository holds 150 skills in this directory. The repository was last updated on August 21, 2026.

Source: ArabelaTso/Skills-4-SE on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.