# PDF Explore > Use this skill when the user has attached a PDF, paper, report, or other document and the answer needs content from more than one place in it: summarize the methods or any other section, compare sections, find where a topic is discussed, read a value or label off a figure or chart, or find/list/extract every instance of something across the whole document (datasets, benchmarks, citations, figures, table rows, accession numbers — including appendices). Parses the PDF once with a deterministic Python kernel: `pdf_pages` (pages as persistent text, or high-res images), `pdf_outline` (embedded TOC), `pdf_scan` (a lexical pre-filter that narrows a long doc to candidate pages), `pdf_grep` (regex sweep for exhaustive pattern extraction). You read the shortlist and do the relevance / summary / extraction judgment yourself. For PDF creation/manipulation, use reportlab/pypdf directly. - Skill: `hughyau/pdf-explore` (Agent Skill, multi-file: 3 files) - Install (CLI): `npx skillmds@latest add hughyau/pdf-explore` - Raw SKILL.md: https://api.skillmd.com/api/skills/hughyau/pdf-explore/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Docs & Writing - License: Apache-2.0 - Author: HughYau (https://skillmd.com/u/hughyau) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/hughyau/pdf-explore --- # PDF Explore — navigate a PDF too big to embed A 50-page PDF read in full is ~200K tokens of context. When the answer draws on several sections at once (summarize the methods; compare section 3 and section 5), or when the answer is "every page" (list all the datasets / citations / figures / benchmarks mentioned anywhere in this document), reading the whole thing page-by-page is the expensive way to get it. This skill parses the PDF **once** into persistent text with a deterministic Python kernel, then lets you **narrow** — by outline, by lexical scan, by regex — and read only the pages you actually need, reasoning over them yourself. Nothing you read vanishes: it is ordinary text and ordinary files. ## Setup (any agent, no API key) This is a **pure skill** — `kernel.py` is deterministic Python and *you* (the base model) do all the reasoning. There is no `host` runtime and no LLM API. Load the helpers once per session in a Python cell: ```python exec(open("/pdf-explore/kernel.py").read()) # adjust the path to wherever this skill is installed ``` Nothing auto-loads it outside Claude Science. Then call the helpers directly (no import). If a helper is "not defined", you haven't `exec`'d `kernel.py` yet — go back and run the line above. Dependencies: `pip install pypdfium2 pillow` (pillow does the PNG encoding for `mode="image"`; it is not pulled in by the pypdfium2 wheel). ## Which helper | | when | returns | |---|---|---| | **`pdf_pages(path, pages=[...], mode="text")`** | you need several pages/sections *at the same time* — summaries, comparisons, anything where the answer draws on more than one range | `[{page, text, n_chars}, ...]` — persistent text; write to a file then read it | | **`pdf_outline(path)`** | structured doc (paper, report, book) with an **embedded** TOC | `[{page, heading, level}, ...]` — the embedded outline, or `[]` if the PDF has none | | **`pdf_scan(path, query, top_k)`** | narrow a long doc to a handful of candidate pages for a query | `{hits: [{page, score, matched, text}], n_scanned}` — a **lexical pre-filter** (no LLM); *you* read the shortlist and judge relevance | | **`pdf_grep(path, pattern)`** | **exhaustive** regex sweep (DOIs, accession ids, every "Table N", emails) | `[{page, matches, lines?}, ...]` — every match with its page | | **`pdf_pages(mode="image", dpi=200)`** | read a small value, axis label, or legend off a **figure** | `[{page, image_path}, ...]` — open the PNG with your agent's image tool | These come from `kernel.py` — load it via `exec` once per session (see **Setup**), then call directly. `pdf_resolve(path)` normalizes a path (a workspace path or a `~/`-expanded path); the helpers call it internally, so `path` can be either form. Note: the default backend is pypdfium2 (Google PDFium; permissive Apache-2.0/BSD-3-Clause). PyMuPDF is honored as a fallback if already installed, but it is AGPL-3.0-licensed (commercial licenses available from Artifex): if you embed it in a network-accessible service, AGPL's source-sharing terms apply to that service. ## Recipe — pull the sections you need as persistent text (synthesis) For "summarize the methods" / "compare section 3 and section 5" / anything where the answer draws on several page ranges at once, pull **all** the pages you need in **one** python call, write them to a file, then read that file: ```python wanted = [5, 21,22,23,24,25, 62,63,64, 124,125,126] # from pdf_outline with open("sections.txt", "w") as f: for p in pdf_pages("paper.pdf", pages=wanted, mode="text"): f.write(f"\n── page {p['page']} ──\n{p['text']}") import os; print(f"wrote {os.path.getsize('sections.txt'):,} bytes") ``` Then read `sections.txt` with your agent's file-read tool (in chunks if it's large) and write the answer from that. It's ordinary text — one parse, and you reason over it directly. **Don't `print()` a full chapter** into the cell output: most agents spill large cell output to disk and make you re-read it anyway, so writing + reading a file costs the same two steps without the wasted preview. (For a quick look at ≤5 pages, printing is fine.) Text is ~800 tokens/page vs ~4,000 tokens/page as vision, and you pay it once. Find the page numbers from `pdf_outline` (below) or the paper's own table of contents first. ## Recipe — navigate by outline (try this first) ```python for e in pdf_outline("report.pdf"): print(f"p{e['page']:>3} {' ' * (e['level'] - 1)}{e['heading']}") # → then pull the section you want with pdf_pages(pages=[...]) ``` Free and instant when the PDF has an embedded outline (most LaTeX-compiled papers do). `pdf_outline` reads the **embedded** TOC only — if the PDF has none it returns `[]`. In that case **build the outline yourself**: pull the first handful of pages (or a stride sample of a long doc) as text with `pdf_pages` and pick out the headings by reading them. For a semantic question the outline doesn't obviously answer ("where do they discuss limitations"), fall through to `pdf_scan`. ## Recipe — find the pages relevant to a query `pdf_scan` ranks pages by **lexical** overlap with your query — it is a cheap **pre-filter**, not a relevance judgment. It narrows a long document to a handful of candidate pages; *you* then read those pages and decide which actually answer the question. ```python r = pdf_scan("paper.pdf", query="batch-effect correction methods", top_k=8) for h in r["hits"]: print(f"p{h['page']} score={h['score']:.2f} matched={h['matched']}") print(f"[{r['n_scanned']} pages scanned]") ``` Then read the shortlist's text and make the final call yourself: ```python for h in r["hits"]: print(f"\n── page {h['page']} ──\n{h['text'][:2000]}") ``` Keep the pages that genuinely address the query; discard lexical false positives (a page that merely says "batch" in another sense). Because the ranking is lexical, a synonym the query didn't use won't score — so lean on your own reading, broaden `top_k` if the shortlist looks thin, and if the term is one you can spell out, cross-check with `pdf_grep` or `pdf_outline`. To skim hit pages as images (layout, tables) instead of text, render them and open the PNGs with your agent's image tool — but a full page is too low-res to read small values off a figure; for that use the next recipe. ```python for p in pdf_pages("paper.pdf", mode="image", pages=[h["page"] for h in r["hits"]], dpi=150): print(p["image_path"]) # open each with your image tool ``` ## Recipe — read a figure in detail A full rendered page is often too low-resolution to read small axis labels, legend text, or values off a dense multi-panel figure. **Render the page at high DPI, then crop the figure region before viewing it** — the crop is both more legible and cheaper (fewer vision tokens than the whole page). ```python # 1. Find the figure's page (pdf_scan on the caption text, pdf_grep on the # figure label, pdf_outline, or you already know it). # 2. Render that page at dpi=200 — high enough to crop into. p = pdf_pages("paper.pdf", mode="image", pages=[5], dpi=200)[0] # 3. Open p["image_path"] with your agent's image tool to locate the # figure, then crop it yourself with pillow before a close read: from PIL import Image Image.open(p["image_path"]).crop((x0, y0, x1, y1)).save("fig_crop.png") # (x0,y0,x1,y1) are pixels in the dpi=200 render. # 4. Open fig_crop.png with your image tool. ``` Crop to one panel at a time for multi-panel figures. Always crop from the full-resolution render on disk, not from an already-downsampled view. ## Recipe — list / extract every instance of X across the doc Two shapes, depending on whether X has a pattern. **Pattern-shaped X** (DOIs, accession numbers, "Figure N", emails, anything you can write a regex for) → `pdf_grep`, an exhaustive regex sweep over the parsed text: ```python hits = pdf_grep("paper.pdf", r"10\.\d{4,9}/[-._;()/:A-Za-z0-9]+") # DOIs for h in hits: print(f"p{h['page']}: {h['matches']}") dois = sorted({m for h in hits for m in h["matches"]}) ``` Returns `[{page, matches, lines?}]` — every match with its page, so you can build a page-indexed list. Exhaustive by construction (regex over every page) and free. **Judgment-shaped X** (datasets results are *actually reported on*, key claims, figure captions, table rows) — no regex captures it, so **you read and extract**. Narrow first if you can (`pdf_outline` to the results section, or `pdf_scan` / `pdf_grep` on a likely term), then pull those pages as text and read them: ```python # e.g. every dataset RESULTS are reported on (not merely cited) cand = {h["page"] for h in pdf_scan("paper.pdf", query="dataset benchmark evaluated", top_k=20)["hits"]} with open("cand.txt", "w") as f: for p in pdf_pages("paper.pdf", pages=sorted(cand)): f.write(f"\n── page {p['page']} ──\n{p['text']}") ``` Read `cand.txt` and write the list yourself, applying the inclusion criterion ("reported on, not merely cited") as you read — that judgment is now just your own reading. If the document is short, skip the narrowing: pull **every** page's text into one file and read it straight through — recall-complete, with no filter that could miss anything. De-dupe and normalize as you write the final answer — you have the whole candidate list in context, so collapse "Dataset A" / "DatasetA" / "the A dataset" yourself. The parse is cached (see **Caching**), so pulling a few more doubtful pages in a follow-up call is instant and free. Decide all your doubts up front and fetch them in one `pdf_pages` call rather than dribbling out one-page-at-a-time reads. ## When NOT to use this skill - **A single lookup of 1–4 pages you'll quote immediately**: your agent's own PDF/page read tool is fine. - **Literal keyword / pattern search**: use `pdf_grep`, or filter the extracted text directly — `[p for p in pdf_pages(path) if "Harmony" in p["text"]]`. `pdf_scan` earns its keep on multi-word queries where you want a ranked shortlist to read, not on a single exact term. ## Mode (scanned PDFs) All helpers default to `mode="auto"`: try text extraction; if pages average < 80 extractable characters (scanned document, image-only slide export), re-parse with page rendering so you can read the image. You don't need to set this. `"text"` / `"image"` force one or the other. Note that `pdf_scan` and `pdf_grep` operate on whatever text layer exists — a pure-image scan has none, so for those docs render the pages (`mode="image"`) and read them yourself. ## Cost & budget Text is ~5× fewer tokens per page than a rendered image and it persists, so the winning pattern is: parse once, **narrow** (outline → scan → grep), and read only the pages you land on. For a very large document you can scan a subset via `pages=range(1, n, 3)`, but stride sampling **can miss** a narrow relevant span between unrelated neighbors; prefer `pdf_outline` → read the section you want when the document has structure. ## Caching `pdf_pages` caches on `(abs_path, mtime, mode, dpi)` — a second `pdf_scan` / `pdf_grep` / `pdf_pages` with different arguments on the same file skips re-parsing and re-rendering. Pass `cache=False` to force a fresh parse. Page renders land in `./.cache/pdf-explore/{sha8}-{mtime}/dpi{N}/p{NNN}.png` — copy or point your image tool at the ones you want to view.