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Agent skill

Handbook Backend Development

by polarsource in polarsource/polar

A skill to add a new entry in the section "Backend Development" of the Polar Handbook.

Apache-2.0Auto-check passedBackend & APIs

Install Handbook Backend Development

skills CLI
$ npx skills add polarsource/polar --skill handbook-backend-development -a claude-code

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

GitHub CLI
$ gh skill install polarsource/polar handbook-backend-development --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/polarsource/polar.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/handbook-backend-development .claude/skills/handbook-backend-development && 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
handbook-backend-development
GitHub stars
10k
Token cost
~676 tokens
SKILL.md length
364 words
Files
1
Skills in repo
18
Repo updated
First seen
Licence
Apache-2.0

At a glance

A skill to add a new entry in the section "Backend Development" of the Polar Handbook.

  • Works in 3 steps: Create the file → Explore and draft the content of the entry → Ask for feedback
  • Tasks that involve Backend development
  • SKILL.md covers Step 1: Create the file, Step 2: Explore and draft the… and Step 3: Ask for feedback
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Handbook Backend Development is an agent skill from polarsource/polar. A skill to add a new entry in the section "Backend Development" of the Polar Handbook. Those entries are there to explain concepts, tooling and best practices related to backend development, and are meant to be read by Polar developers.

Its SKILL.md is about 680 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Backend & APIs, covering Backend development, DataFrames and Tutoring and explanations. The repository describes itself as: Polar — A billing platform for the intelligence era. The licence is Apache-2.0.

When your agent uses it

  • Tasks that involve Backend development
  • Tasks that involve DataFrames
  • Tasks that involve Tutoring and explanations

Example prompts

  • “Backend Development”
  • “/handbook-backend-development”

Requirements

  • Pre-approved tools (allowed-tools): Read, Grep, Write

Workflow steps

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

  1. Create the file
  2. Explore and draft the content of the entry
  3. Ask for feedback

What it can do on your machine

Read from SKILL.md and the folder at commit 599c727. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves these tools, so the agent can use them without asking each time:

    • Read
    • Grep
    • Write

    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 mdx).

    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

Handbook Backend Development loads about 676 tokens when it runs. Until then it costs about 66 tokens; SKILL.md has 364 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~66
When it runs · the whole SKILL.md, loaded when a task matches
~676

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 polarsource/polar at commit 599c727, republished under its Apache-2.0 licence (© polarsource). 364 words, ~676 tokens.

Download SKILL.mdSave it as .claude/skills/handbook-backend-development/SKILL.md (or your agent's skills folder).
name
handbook-backend-development
description
A skill to add a new entry in the section "Backend Development" of the Polar Handbook. Those entries are there to explain concepts, tooling and best practices related to backend development, and are meant to be read by Polar developers.
allowed-tools
Read, Grep, Write
user-invocable
true

Handbook - Backend Development

This skill explains the process to add a new entry in the section "Backend Development" of the Polar Handbook. Those entries are there to explain concepts, tooling and best practices related to backend development, and are meant to be read by Polar developers.

The user should explain which concept they want to explain in the new entry, and the skill will guide them through the process of creating the file, exploring the code base to find relevant information, and writing the content of the entry.

Step 1: Create the file

Create an MDX file in handbook/backend-development with a name that reflects the concept you want to explain. For example, if you want to explain how the distributed lock mechanism works, you could name the file distributed-lock.mdx.

Follow the following template for the content of the file:

mdx
---
title: "Title of the entry"
description: "Short description of the entry"
---

Summary of the concept you want to explain.

## When to use this concept

## How to use this concept

## How it works

The three sections "When to use this concept", "How to use this concept" and "How it works under the hood" are here to structure the content of the entry. The first section should explain in which situations the concept is useful, the second section should explain how to use the concept in practice, and the third section should explain how the concept works under the hood, with technical details and references to the code base.

Add this page to the navigation by adding an entry under "Backend Development" in handbook/docs.json.

Show full SKILL.md (135 more words)Show less

Step 2: Explore and draft the content of the entry

To write the content of the entry, you will need to explore the code base to find relevant information about the concept you want to explain. Use it to fill the three sections of the entry with accurate and detailed information. You can also add code snippets, diagrams, or any other type of content that you think is relevant to explain the concept.

Step 3: Ask for feedback

Once you have a draft of the entry, ask for feedback from the user. If you have any doubts about the content, ask for clarification. You can also ask for feedback on the structure and the clarity of the entry. The goal is to make sure that the entry is accurate, clear, and useful for Polar developers.

© polarsource, 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

Just SKILL.md in .agents/skills/handbook-backend-development of polarsource/polar.

Open the folder on GitHubat commit 599c727

Compare with similar skills

Handbook Backend Development 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.

Handbook Backend Development compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Handbook Backend Development this skillpolarsource/polar10k—~676Automated safety check: PassApache-2.0
Arcgis To Portaljsdatopian/portaljs2.4k—~2kAutomated safety check: PassMIT
Mastering Python SkillSpillwaveSolutions/agent-brain120—~1.4kAutomated safety check: NotesMIT
Zarr Pythondavila7/claude-code-templates32k11 repos~5kAutomated safety check: PassMIT
Elasticsearch File IngestKilo-Org/kilo-marketplace189—~2.8kAutomated safety check: PassApache-2.0
Junta Leiloeirossickn33/agentic-awesome-skills47k2 repos~1.6kAutomated safety check: PassMIT

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Categories

Questions about Handbook Backend Development

What does Handbook Backend Development do?

A skill to add a new entry in the section "Backend Development" of the Polar Handbook. Handbook Backend Development is an agent skill from polarsource/polar. A skill to add a new entry in the section "Backend Development" of the Polar Handbook.

When should I use Handbook Backend Development?

Handbook Backend Development fits situations like: tasks that involve Backend development; tasks that involve DataFrames; tasks that involve Tutoring and explanations.

How do I install Handbook Backend Development in Claude Code?

Run `npx skills add polarsource/polar --skill handbook-backend-development -a claude-code`. Or copy the skill folder (.agents/skills/handbook-backend-development in polarsource/polar) into .claude/skills/handbook-backend-development in your project. Claude Code loads it when a task matches its description.

How do I install Handbook Backend Development in Codex?

Run `npx skills add polarsource/polar --skill handbook-backend-development -a codex`. Or copy the skill folder (.agents/skills/handbook-backend-development in polarsource/polar) into .agents/skills/handbook-backend-development in your project. Codex loads it when a task matches its description.

Can I use Handbook Backend Development 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 polarsource/polar --skill handbook-backend-development -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/handbook-backend-development, .gemini/skills/handbook-backend-development, .github/skills/handbook-backend-development and .opencode/skills/handbook-backend-development in your project.

What does Handbook Backend Development need to run?

SKILL.md names no scripts, command-line tools or credentials: Handbook Backend Development is instructions for the agent only. Its frontmatter pre-approves these tools: Read, Grep, Write.

Does Handbook Backend Development 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 Handbook Backend Development 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 Handbook Backend Development use?

Handbook Backend Development 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 Handbook Backend Development use?

About 676 tokens (SKILL.md is roughly 2.7k 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 Handbook Backend Development?

Skills that share tags, products or a category with Handbook Backend Development: Arcgis To Portaljs (datopian/portaljs, 2.4k stars), Mastering Python Skill (SpillwaveSolutions/agent-brain, 120 stars), Zarr Python (davila7/claude-code-templates, 32k stars) and Elasticsearch File Ingest (Kilo-Org/kilo-marketplace, 189 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Handbook Backend Development?

polarsource (a GitHub organization) maintains it in polarsource/polar, which has 10,336 GitHub stars. The repository holds 18 skills in this directory. The repository was last updated on October 7, 2026.

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