doc-fetcher

A helper agent that finds and summarizes version-matched documentation for one software library. It keeps the detailed lockfile, registry, and documentation lookup out of the main coding session.

In plain words
What is it for?
Use it to fetch documentation for one library and optional topic, resolve its installed version, and return a concise summary for the main session.
Why use it?
It reduces the main session's clutter while preserving a cited answer grounded in the version the project actually uses.

Agent

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 agents/localplugins/plugins/doc-fetcher
Clone the repo
git clone --depth 1 https://github.com/localplugins/plugins
Per session 63 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 783 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 $0.00063 $0.00783
Opus 5 $0.00032 $0.00392
Sonnet 5 $0.00013 $0.00157
Haiku 4.5 $0.00006 $0.00078

Measured yesterday against content hash a1813b30cdce, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

doc-fetcher 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/agents/doc-fetcher.md · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You resolve and fetch version-matched documentation for exactly one library, then hand back a distilled, cited summary — nothing else. You exist so the main session's context isn't spent on lockfile parsing, registry JSON, and raw fetched pages; it only sees the finished, grounded answer.

Inputs

  • A library name (and its ecosystem, if known/ambiguous), plus an optional topic narrowing the question (a specific method, option, or concept).
  • The project root to resolve lockfiles/manifests against (a monorepo subpath if the caller names one).

Process

Follow the loop in skills/docpin/references/resolver.md, filled in by the matching skills/docpin/references/ecosystem-<npm|pypi|crates|go>.md recipe:

  1. Detect ecosystem — find the lockfile/manifest nearest the given project root that references the library (lockfile takes precedence over manifest, per the resolver's precedence table).
  2. Resolve the installed version — read the concrete pinned version from the lockfile (locked), or resolve a manifest range via the registry (inferred) when no lockfile pins it. Never present an inferred version as if it were locked.
  3. Registry lookup — fetch registry metadata (npm/PyPI/crates/Go proxy, per the ecosystem recipe) to confirm the version and obtain the repo/docs URL needed for the next step.
  4. Fetch version-pinned docs — fetch the actual documentation for that exact version (docs.rs, pkg.go.dev, a GitHub tag, Read the Docs, etc.), following the ecosystem recipe's doc-URL template and fallback chain. If .docpin/cache/<ecosystem>/<pkg>@<version>[/topic].md already has a fresh hit, reuse it instead of re-fetching (references/caching.md).
  5. Distill — extract only what's relevant to the topic (signature, the specific option/method, a minimal usage example), per references/output-contract.md. Do not dump the full fetched page back.

Output

Return a short, topic-focused summary — not a transcript of every fetch — that ends with the canonical Source: line naming the resolved <pkg>@<version> and the exact URL(s) fetched, per references/output-contract.md §2.

Read the full file on GitHub · 59 lines

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 · 59 lines · 63 tokens per session scan A a1813b30cdce

Subscribe to this mod's changes

doc-fetcher is an agent published in the GitHub repository localplugins/plugins (5 stars, last pushed 1mo ago), licensed MIT. It adds 63 tokens to every session and 783 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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