Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/paritytech/polkadot-appsnpx agentmods add skills/paritytech/polkadot-apps/polkadot-app-builderWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/paritytech/polkadot-apps/polkadot-app-builder)<a href="https://agentmods.dev/skills/paritytech/polkadot-apps/polkadot-app-builder"><img src="https://agentmods.dev/badge/skills/paritytech/polkadot-apps/polkadot-app-builder/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/paritytech/polkadot-apps/polkadot-app-builder"><img src="https://agentmods.dev/badge/skills/paritytech/polkadot-apps/polkadot-app-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00089 | $0.01988 |
| Opus 5.5 | $0.00036 | $0.00795 |
| Sonnet 5.5 | $0.00018 | $0.00398 |
| Haiku 4.5 | $0.00009 | $0.00199 |
Grade A, and why
polkadot-app-builder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 211 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Polkadot App Builder
Orchestrator skill for building applications with the @polkadot-apps package ecosystem.
Quick Start
Preset Path (zero-config for known environments)
import { getChainAPI } from "@polkadot-apps/chain-client";
const client = await getChainAPI("paseo");
const balance = await client.assetHub.query.System.Account.getValue("5GrwvaEF...");
client.destroy();
BYOD Path (Bring Your Own Descriptors)
import { createChainClient } from "@polkadot-apps/chain-client";
import { paseo_asset_hub } from "@polkadot-apps/descriptors/paseo-asset-hub";
const client = await createChainClient({
chains: { assetHub: paseo_asset_hub },
rpcs: { assetHub: ["wss://sys.ibp.network/asset-hub-paseo"] },
});
const balance = await client.assetHub.query.System.Account.getValue("5GrwvaEF...");
client.destroy();
Workflow
1. Understand Requirements
Determine what the app needs:
- Read chain state (balances, storage, block info)
- Submit transactions (transfers, remarks, contract calls)
- Store data on Bulletin Chain
- Real-time messaging via Statement Store
- Address utilities (SS58, H160 conversion)
- Encryption (AES, ChaCha20, NaCl)
- Key management (derivation, session keys)
2. Select Packages
Use the decision tree in references/package-selector.md.
Every app needs:
@polkadot-apps/chain-client # Connect to chains
@polkadot-apps/descriptors # Chain type definitions (peer dep of chain-client)
polkadot-api # Core runtime (peer dep of descriptors)
Add based on features:
| Feature | Package | Skill |
|---|---|---|
| Smart contracts (Solidity/ink!) | @polkadot-apps/contracts |
polkadot-contracts |
| Submit transactions | @polkadot-apps/tx |
polkadot-transactions |
| Wallet connection (Talisman, Polkadot.js, Host API) | @polkadot-apps/signer |
polkadot-transactions |
| Key derivation | @polkadot-apps/keys |
polkadot-transactions |
| Decentralized storage | @polkadot-apps/bulletin |
polkadot-bulletin |
| Pub/sub messaging | @polkadot-apps/statement-store |
polkadot-statement-store |
| Address encoding | @polkadot-apps/address |
polkadot-utilities |
| Encryption | @polkadot-apps/crypto |
polkadot-utilities |
| KV storage | @polkadot-apps/storage |
polkadot-utilities |
| Logging | @polkadot-apps/logger |
polkadot-utilities |
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 211 lines · 89 tokens per session scan A 677af340907f
polkadot-app-builder is a skill published in the GitHub repository paritytech/polkadot-apps (2 stars, last pushed 3d ago), licensed Apache-2.0. It adds 89 tokens to every session and 1,988 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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