Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add barnburner121/claude-plugin-marketplace --skill chain-idxgit clone --depth 1 https://github.com/barnburner121/claude-plugin-marketplaceWrote 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/barnburner121/claude-plugin-marketplace/chain-idx)<a href="https://agentmods.dev/skills/barnburner121/claude-plugin-marketplace/chain-idx"><img src="https://agentmods.dev/badge/skills/barnburner121/claude-plugin-marketplace/chain-idx/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/barnburner121/claude-plugin-marketplace/chain-idx"><img src="https://agentmods.dev/badge/skills/barnburner121/claude-plugin-marketplace/chain-idx.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 | $0.00009 | $0.00070 |
| Opus 5 | $0.00005 | $0.00035 |
| Sonnet 5 | $0.00002 | $0.00014 |
| Haiku 4.5 | $0.00001 | $0.00007 |
Grade A, and why
chain-idx 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 8d 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.
The source is not reproduced here
No licence file
A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.
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.
- 8d ago First seen · 10 lines · 9 tokens per session scan A b95ad70e3a8c
chain-idx is a skill published in the GitHub repository barnburner121/claude-plugin-marketplace (3 stars, last pushed 5mo ago), with no licence file. It adds 9 tokens to every session and 70 once invoked, about $0.0000 per session on Opus 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 2026-09-03.
Other skills, from other repositories
bitcoin-core-operations
Running Bitcoin Core in production: bitcoin.conf reference, sections, pruning, signet, dbcache, mempool tuning, network bind, Tor, IBD considerations, debug.log analysis. USE WHEN: deploying a node, tuning performance, debugging IBD issues, configuring multi-network nodes.
bitcoin-bip32
BIP32 hierarchical deterministic key derivation: master key from seed, hardened vs unhardened derivation, xpub/xprv encoding, fingerprints, child-key chaining, key origin paths. USE WHEN: building HD wallets, deriving addresses, parsing xpubs, validating descriptors with key origin.
bitcoin-musig2
MuSig2 (BIP327): two-round Schnorr key aggregation for n-of-n multisig. Aggregates n public keys into a single 32-byte x-only pubkey indistinguishable from a single-sig. Used in Taproot cooperative spends. Quick refs: protocol round-trip, key aggregation math, common attacks. USE WHEN: implementing n-of-n cooperative…
bitcoin-core-release-engineering
Bitcoin Core release engineering: Guix reproducible builds, signed release tarballs, deterministic outputs, code-signing keys, the release process, security disclosure. USE WHEN: building Bitcoin Core from source for verification, understanding release security, contributing to consensus-critical code.
bitcoin-dlcs
Discreet Log Contracts: smart contracts on Bitcoin via oracle attestations + adaptor signatures. Oracle publishes nonces upfront, reveals signed outcomes; CETs (Contract Execution Transactions) enforce payouts. No on-chain footprint of the contract logic. USE WHEN: building betting / prediction markets, parametric…
bitcoin-l2-fedimint
Fedimint: federated Chaumian e-cash on Bitcoin with Lightning gateway. Multi-sig guardians, blind-signature notes, community-scale custody with privacy. Fedi mobile wallet. USE WHEN: deploying community mints, integrating federated e-cash, evaluating Fedimint vs Cashu.