Research is the category most easily faked by looking like research: numbered citations, confidence markers, a counter-evidence section. Format reads as credible far more readily than content does. All ten items below open in a browser, and the test is single: does it leave behind something you can check afterwards?
Writing has no oracle. Research has half of one: whether a citation opens, whether the date is right, whether the sentence is actually what that source said — a machine can settle the first two. So the real divide in this category is not who writes the deepest report, but who leaves a second, checkable ledger alongside it: a citation registry, source-type labels, and the sources that were dropped along with why. Install commands below are copied from each project's own page. Section 02 explains why these ten belong to three layers and cannot be compared as one list, section 03 gives six things you can check in three minutes with SKILL.md open, and section 04 lays out the costs.
# 1 — 59 directories in that repo. Copy the two or three you want, not all of it.
/plugin marketplace add daymade/claude-code-skills
git clone --depth 1 https://github.com/daymade/claude-code-skills /tmp/dcs
cp -r /tmp/dcs/deep-research /tmp/dcs/competitors-analysis /tmp/dcs/fact-checker ~/.claude/skills/
# 2 — note: also named deep-research, same target directory as 1. Pick one.
git clone https://github.com/199-biotechnologies/claude-deep-research-skill.git ~/.claude/skills/deep-research
# 3 — clone the repo first, then copy. English and Chinese sets, plus Codex / OpenCode variants.
cp -r skills/research-en/* ~/.claude/skills/
cp agents/web-search-agent.md ~/.claude/agents/
cp -r agents/web-search-modules ~/.claude/agents/
pip install pyyaml
# 4 — pulls in 31 skills at once. Worth it only if you write papers.
npx skills add lingzhi227/agent-research-skills -g -a claude-code
# 5 — official, and a plugin of its own: it is not inside example-skills.
/plugin marketplace add anthropics/skills
/plugin install discernment-nudge@anthropic-agent-skills
# 6 — one project, two forms. This is the skill install; MCP install is in the repo.
uv tool install paper-search-mcp
mkdir -p ~/.claude/skills/paper-search
curl -fsSL https://raw.githubusercontent.com/openags/paper-search-mcp/main/claude-code/SKILL.md \
-o ~/.claude/skills/paper-search/SKILL.md
# 7-10 — the retrieval layer. Pick one, at most two.
uvx arxiv-mcp-server # 7 into mcpServers; papers land in ~/.arxiv-mcp-server/papers
claude plugin install exa@claude-plugins-official # 8 two tools by default
env FIRECRAWL_API_KEY=fc-YOUR_API_KEY npx -y firecrawl-mcp # 9 twenty-five tools by default
npx -y tavily-mcp@latest # 10 four tools, API key required
# Do this immediately after installing
/skill-doctor # context cost and invocation frequency per skill
deep-research SKILL.md pins the procedure to phases P0-P7, and the hinge is P3, where it builds a citation registry — deduplicating, numbering, and recording every dropped source with the reason it was dropped. Once the registry is final, the draft may cite only from it. Three hard rules follow: reopen the original for every load-bearing claim; never invent a URL, every locator comes from an actual retrieval; mark [Unverified] or omit rather than speculate. In the same repo, competitors-analysis demands that repository-level findings come from locally cloned code while market-level claims cite a source, and fact-checker only proposes corrections for your approval. The catch: 59 directories, so installing the lot means 59 descriptions in context every turn.validate_report.py (nine checks) and verify_citations.py (DOI / URL / hallucination detection), inside a validate-fix-retry loop capped at three cycles, with a floor of "10+ sources, 3+ per major claim". Multi-provider search needs search-cli and your own key for something like Brave.research-en and research-zh plus a Codex build, so portability across harnesses is its selling point. The price is a manual cp install, an extra web-search-agent to copy, and pip install pyyaml.literature-search and novelty-assessment, then experiment-design, paper-writing-section, related-work-writing, then self-review, rebuttal-writing, slide-generation. Discovery runs against four APIs: Semantic Scholar, arXiv, OpenAlex and CrossRef. It is the list's example of "the narrower the domain, the more sense a bulk install makes": a pipeline if you write papers, 31 wasted descriptions if you do not.anthropics/skills (177k stars on that repo per its GitHub page, 2026-09) — the lightest item here and the most underrated. It does no research; it changes the posture in which you receive an answer. After a substantive answer you might act on, it appends two or three follow-up questions tied to specifics in what was just produced, to help you check key facts, probe assumptions and notice missing context — at most once per conversation. Most of its description is spent on when not to fire: trivial how-tos, purely educational explanations, formatting or assembly work, code you will run, creative writing, and anything you already asked it to double-check. That "when not to" clause being longer than the rest is itself a model for writing skills.paper-search, and the skill form needs no MCP configuration at all. It covers more than twenty sources including arXiv, PubMed, bioRxiv, medRxiv, Semantic Scholar, OpenAlex, CrossRef, Europe PMC, dblp, Zenodo, HAL and SSRN, on a free-first strategy: most sources need no key, while Semantic Scholar, CORE and Unpaywall are steadier with one.~/.arxiv-mcp-server/papers and stay there, you can read a named section of the original LaTeX instead of a summary of a summary, BibTeX comes straight out of arXiv metadata, and topic watches are built in. The core needs no external search service; a Semantic Scholar key only makes citation lookups more reliable.web_search_exa and web_fetch_exa by default, with agent_run and others behind an explicit switch. The hosted endpoint works anonymously under rate limits; a key or OAuth lifts them. On the tool-slot budget it is the most restrained item here — compare it with item 9.firecrawl_research_* paper tools, plus eight firecrawl_monitor_* ones. Those eight are where the competitive-intelligence thread finally lands on real tooling: create a watch, run a check, see which page of a site changed. The cloud API needs a key; FIRECRAWL_API_URL points it at a self-hosted instance instead.tavily-search, tavily-extract, tavily-map, tavily-crawl. The tool count sits between items 8 and 9, which makes it the middle option when you need whole-site traversal but not twenty-five tool definitions. A key is required.One common install is simply wrong: items 1 and 2 together. Both target ~/.claude/skills/deep-research, so the names collide; and even after you rename a directory, the two descriptions compete for the same trigger ("research this topic", "write a report on"), so which procedure runs is a coin flip. Pick exactly one process-layer skill. That one is not negotiable.
The reverse is more common still: a carefully chosen process layer and no retrieval at all. Item 1's rule about reopening originals for load-bearing claims then lands on default web search, which surfaces the same aggregator pages as before. No procedure is stricter than the eyes it calls. Papers mean items 6 and 7; watching a competitor's site means item 9's firecrawl_monitor_*; wanting accurate search without burning tool slots means item 8.
Item 4 is a third kind of thing: not general research but a disciplinary pipeline. Pointed at market research it feels wrong, because rebuttal-writing and latex-formatting will never fire in that context while still costing description budget every turn. The test is easy: does your output carry a bibliography? If yes, install it; if no, do not.
[Unverified], confidence markers, an explicit "say you could not find it". A research skill that is not allowed to output "I do not know" will encode uncertainty as certainty, because you left it only one exit.AS_OF at P0 and requires a source date on every time-sensitive claim. Without it, last year's figure and this year's get written into the same sentence as equals.verify_citations.py tests whether a DOI or URL exists; validate_report.py runs nine checks. This is the only thing in the category that catches errors without reading the content. Mind its boundary, though — see section 04.search-cli), or an MCP server it assumes you already installed? When that assumption fails it does not error — it degrades quietly.If three of these six have no answer, what you have bought is the layout of research, not research.
Anthropic published its own numbers: per its engineering post "How we built our multi-agent research system", 2025-06, Research runs an orchestrator-worker pattern — a lead agent plans, spawns subagents that work in parallel with their own context windows, and merges their findings with a separate citation pass. The return was a 90.2% improvement on their internal research eval for an Opus 4 lead with Sonnet 4 subagents; the price is roughly 15x the tokens of an ordinary chat interaction, and the same post is explicit that this architecture is a poor fit for tightly interdependent work such as coding. Items 1 and 2, with their lead-plus-subagents structure, spend exactly that. Budget a deep report like a compile, not like a question.
Item 9 ships 25 tool definitions by default; item 8 ships 2. Those definitions sit in context every turn whether or not you use them. Count tools before installing a second retrieval server — and the same arithmetic applies to item 1's 59 directories and item 4's 31 skills, where a bulk install is a description tax paid each turn. Run /skill-doctor afterwards: it reports the context cost and invocation frequency of every skill you have.
verify_citations.py can confirm that a DOI exists and a URL resolves, but it does not check whether the sentence is what that source said. A link that is real, numbered neatly, and does not actually support the claim attached to it is this category's most frequent false positive — and it passes every automated check by construction.The second trap is that format reads as more credible than content. Numbered citations, confidence markers and a "counter-evidence" section are all visual signals of rigor. A skill that only applies the layout, without ever reopening an original, produces something indistinguishable on screen from real work. The six criteria in section 03 are, at bottom, one question asked six ways: is there a ledger behind this layout?
Third, nearly all of these default to the open web, so second-hand aggregators get treated as sources — Skill 21 on this site takes that apart on its own.
Install these three first: deep-research from daymade/claude-code-skills (copy that one directory, not all 59; you are buying the P3 citation registry and the [Unverified] exit) + exa-mcp-server (claude plugin install exa@claude-plugins-official, two tool slots, a decent pair of eyes for the process layer) + discernment-nudge (/plugin install discernment-nudge@anthropic-agent-skills, official, lightest here, fires once per conversation).
Add as needed: openags/paper-search-mcp (papers, most sources key-free) · blazickjp/arxiv-mcp-server (when you want BibTeX and papers archived on disk) · Weizhena/Deep-Research-skills (swap it in for the process layer above when you want a human gate at the outline) · 199-biotechnologies/claude-deep-research-skill (when you want checks that actually run, like verify_citations.py) · item 9's firecrawl_monitor_* (when you really are watching a competitor's site) · tavily-mcp (site map and crawl without twenty-five tools) · lingzhi227/agent-research-skills (when you genuinely write papers).
Explicitly do not install: items 1 and 2 at once (same ~/.claude/skills/deep-research directory, same trigger) · a process layer with no retrieval server at all (a strict procedure wired to default eyes) · firecrawl-mcp's 25 tools for a one-off search · all 31 skills of agent-research-skills when you write no papers.
Three things after installing: run /skill-doctor and count tool slots and context cost · walk your chosen process layer through the six checks in section 03 · set yourself one floor — for any number you will act on, open the citation yourself.
/plugin marketplace add install and the 59-directory listing (1.4k stars, 2026-09); deep-research · SKILL.md for P0-P7, the P3 registry, [Unverified] and evidence families; competitors-analysis · SKILL.md for "repository findings must come from local clones"validate_report.py (nine checks) and verify_citations.py (DOI/URL/hallucination), with a three-cycle validate-fix-retry loop (1.0k stars, MIT, 2026-09)research-en / research-zh and the Codex / OpenCode variants (2.2k stars, MIT, 2026-09)web_search_exa and web_fetch_exa by default; hosted endpoint usable anonymously (5.0k stars, MIT, 2026-09)firecrawl_monitor_* site-change watchers and the firecrawl_research_* set (7.5k stars, MIT, 2026-09)tavily-search, extract, map and crawl (2.4k stars, MIT, 2026-09)/skill-doctor for context cost and invocation frequency (2026-09)