docpin

A version-matched documentation lookup tool finds the installed version of a third-party library and uses documentation for that version. Third-party libraries are packages made by others and added to a project.

In plain words
What is it for?
Use it before writing or explaining code that imports a package from npm, PyPI, crates.io, or Go, or when asking how a named library or framework works.
Why use it?
It reduces errors caused by relying on documentation for a different release or on remembered API details. It also avoids unnecessary lookups for built-in language features.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/localplugins/plugins/docpin
Any agent
npx skills add localplugins/plugins --skill docpin
Clone the repo
git clone --depth 1 https://github.com/localplugins/plugins

Made for: Claude Code, Codex.

Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 854 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00050 $0.00854
Opus 5 $0.00025 $0.00427
Sonnet 5 $0.00010 $0.00171
Haiku 4.5 $0.00005 $0.00085

Measured yesterday against content hash 66abb37f1ecd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

docpin 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 yesterday.

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.

docpin/skills/docpin/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

docpin

Ground library code in documentation for the exact version installed in this project — not training-data memory, and not merely "latest."

When to trigger

  • Claude is about to write or explain code that imports/calls a third-party library (npm, PyPI, crates.io, or Go module).
  • The user asks how to use a named library or framework ("how do I do X with <lib>", "why isn't <lib>.foo() working", etc.).

When NOT to trigger

  • Standard-library / language-builtin APIs (e.g. Python's os, Node's fs, Rust's std, Go's net/http) — these aren't version-pinned third-party packages and don't need registry resolution.
  • Pure algorithm/logic questions with no library API surface involved.
  • The project already has a fresh cache hit for this exact pkg@version (see references/caching.md) — reuse it instead of re-fetching.

The resolve → fetch → ground loop

Five steps, detailed in references/resolver.md:

  1. Detect ecosystem — find the lockfile/manifest nearest the file in focus (lockfile takes precedence over manifest).
  2. Resolve installed version — read the concrete pinned version from the lockfile, or infer one from a manifest range via the registry.
  3. Registry lookup — fetch registry metadata to confirm the version and get the repo/docs URLs.
  4. Fetch version-pinned docs — fetch the actual docs for that exact version, per the ecosystem's recipe.
  5. Distill + ground — extract what's relevant, then write or explain code against it, citing the version and URL.

For the full algorithm, the file-precedence table, the registry URLs, and the fallback chain (no lockfile, 404, private package), read references/resolver.md.

Honesty invariant

Every grounded answer must:

  • Cite the resolved version and the exact URL(s) fetched, so the user can verify.
  • Never invent a symbol that isn't present in the resolved version's docs — if a requested API isn't there, say so plainly (e.g. "useFooBar is not in [email protected]") instead of guessing or fabricating.

Read the full file on GitHub · 80 lines

Files

What ships with it

7 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.

Changes

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.

  1. yesterday First seen · 80 lines · 50 tokens per session scan A 66abb37f1ecd

Subscribe to this mod's changes

docpin is a skill published in the GitHub repository localplugins/plugins (5 stars, last pushed 1mo ago), licensed MIT. It adds 50 tokens to every session and 854 once invoked, about $0.0003 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 2026-08-31.

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