---

name: scientific-literature-search description: "Query authoritative scientific databases (PubMed, Semantic Scholar) for medical literature. Use when user asks about research on conditions, mechanisms, treatments, or when investigate-root-cause needs scientific evidence for biological mechanisms."

Scientific Literature Search

Query PubMed and Semantic Scholar for authoritative medical and scientific literature to support hypothesis generation, mechanism exploration, and evidence-based analysis.

Use Cases

Use this skill when:

• User asks: "Find papers on [condition/mechanism]"
• User asks: "What does research say about [topic]?"
• User asks: "Latest therapies for [condition]"
• investigate-root-cause needs biological mechanisms (replaces generic WebSearch)
• mechanism-search needs authoritative citations
• Hypothesis generation requires scientific backing

Data Sources

PubMed (NCBI E-utilities)

• Coverage: 36+ million biomedical citations (MEDLINE, life science journals, online books)
• Authority: Gold standard for medical literature (NIH/NLM curated)
• API: E-utilities (esearch + efetch)
• Rate Limit: 3 req/s (10 req/s with API key)
• Best For: Clinical research, disease mechanisms, drug trials

Semantic Scholar

• Coverage: 200+ million papers across all sciences
• Authority: AI-powered relevance ranking, citation graph analysis
• API: Academic Graph API
• Rate Limit: 1000 req/s (shared, unauthenticated)
• Best For: Comprehensive search, paper discovery, citation networks

Workflow

Step 1: Load Environment Variables

Check for NCBI API key (optional but recommended):

Copy# Check if .env file exists
if [ -f .env ]; then
  source .env
  echo "NCBI API key loaded: ${NCBI_API_KEY:0:8}..."
else
  echo "No .env file found. Using default rate limit (3 req/s)."
  echo "To enable 10 req/s: Create .env file with NCBI_API_KEY (see .env.example)"
fi

Step 2: Parse Query and Generate Search Terms

Extract search query from user input:

Copyquery="$1"  # e.g., "hereditary spherocytosis osmotic fragility sensitivity"

# Sanitize query for URLs
query_encoded=$(echo "$query" | sed 's/ /+/g')

# Generate cache key (SHA256 of query)
cache_key=$(echo -n "$query" | shasum -a 256 | awk '{print $1}')
cache_file=".claude/skills/health-agent/scientific-literature-search/.cache/${cache_key}.json"

Step 3: Check Cache (30-day TTL)

Copy# Check if cached results exist and are fresh (30 days)
if [ -f "$cache_file" ]; then
  file_age_days=$(( ($(date +%s) - $(stat -f %m "$cache_file")) / 86400 ))

  if [ $file_age_days -lt 30 ]; then
    echo "✅ Cache hit (age: ${file_age_days} days). Using cached results."
    cat "$cache_file"
    exit 0
  else
    echo "⚠️ Cache expired (age: ${file_age_days} days). Fetching fresh results..."
    rm "$cache_file"
  fi
fi

echo "❌ Cache miss. Querying PubMed and Semantic Scholar..."

Step 4: Query PubMed E-utilities

Copy# Step 4a: Search PubMed for matching articles (esearch)
if [ -n "$NCBI_API_KEY" ]; then
  api_key_param="&api_key=$NCBI_API_KEY"
else
  api_key_param=""
fi

pubmed_search_url="https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=pubmed&term=${query_encoded}&retmax=10&retmode=json&sort=relevance${api_key_param}"

pubmed_ids=$(curl -s "$pubmed_search_url" | grep -oP '"idlist":\[\K[^\]]+' | tr ',' '\n' | tr -d '"')

if [ -z "$pubmed_ids" ]; then
  echo "No PubMed results found for query: $query"
  pubmed_results="[]"
else
  # Step 4b: Fetch article details (efetch)
  pmids=$(echo "$pubmed_ids" | head -10 | tr '\n' ',' | sed 's/,$//')

  pubmed_fetch_url="https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esummary.fcgi?db=pubmed&id=${pmids}&retmode=json${api_key_param}"

  pubmed_data=$(curl -s "$pubmed_fetch_url")

  # Parse JSON and extract fields (title, authors, year, PMID, DOI)
  pubmed_results=$(echo "$pubmed_data" | jq -r '
    .result
    | to_entries
    | map(select(.key != "uids"))
    | map({
        pmid: .value.uid,
        title: .value.title,
        authors: (.value.authors[:3] | map(.name) | join(", ")),
        year: .value.pubdate[:4],
        doi: (.value.articleids // [] | map(select(.idtype == "doi")) | .[0].value // "N/A"),
        source: "PubMed"
      })
  ')
fi

Step 5: Query Semantic Scholar

Copy# URL encode query for Semantic Scholar
ss_query_encoded=$(echo "$query" | jq -sRr @uri)

ss_search_url="https://api.semanticscholar.org/graph/v1/paper/search/bulk?query=${ss_query_encoded}&limit=10&fields=title,authors,year,abstract,citationCount,openAccessPdf,externalIds"

ss_data=$(curl -s -H "User-Agent: health-agent/1.0" "$ss_search_url")

# Parse results
ss_results=$(echo "$ss_data" | jq -r '
  .data
  | map({
      title: .title,
      authors: (.authors[:3] | map(.name) | join(", ")),
      year: .year,
      doi: (.externalIds.DOI // "N/A"),
      pmid: (.externalIds.PubMed // "N/A"),
      citation_count: .citationCount,
      abstract: (.abstract[:300] + "..." // "N/A"),
      pdf_url: (.openAccessPdf.url // "N/A"),
      source: "Semantic Scholar"
    })
')

if [ "$ss_results" = "null" ] || [ -z "$ss_results" ]; then
  ss_results="[]"
fi

Step 6: Merge Results and Sort by Relevance

Copy# Combine PubMed and Semantic Scholar results
combined_results=$(jq -s '.[0] + .[1] | sort_by(-.citation_count // 0)' <(echo "$pubmed_results") <(echo "$ss_results"))

# Add metadata
output=$(jq -n \
  --arg query "$query" \
  --arg timestamp "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  --argjson results "$combined_results" \
  '{
    query: $query,
    fetched_at: $timestamp,
    ttl_days: 30,
    total_results: ($results | length),
    results: $results
  }')

# Save to cache
echo "$output" > "$cache_file"

# Output results
echo "$output"

Step 7: Format Output as Markdown

Copy# Parse JSON and generate markdown table
echo "## Scientific Literature Search Results"
echo ""
echo "**Query**: $query"
echo "**Total Results**: $(echo "$output" | jq -r '.total_results')"
echo "**Fetched**: $(echo "$output" | jq -r '.fetched_at')"
echo ""
echo "| Title | Authors | Year | Source | PMID/DOI | Citations |"
echo "|-------|---------|------|--------|----------|-----------|"

echo "$output" | jq -r '.results[] | "| \(.title) | \(.authors) | \(.year) | \(.source) | \(if .pmid != "N/A" then "PMID:\(.pmid)" else "DOI:\(.doi)" end) | \(.citation_count // 0) |"'

echo ""
echo "### Abstracts (Top 5 Results)"
echo ""

echo "$output" | jq -r '.results[:5] | .[] | "#### \(.title) (\(.year))\n\n**Authors**: \(.authors)\n**Source**: \(.source)\n**Citations**: \(.citation_count // 0)\n\n**Abstract**: \(.abstract // "N/A")\n\n**DOI**: \(.doi)\n**PMID**: \(.pmid)\n\n---\n"'

Complete Script Template

For convenience, here's a complete bash script that implements the entire workflow:

Copy#!/bin/bash
# scientific-literature-search.sh - Query PubMed and Semantic Scholar

query="$1"

if [ -z "$query" ]; then
  echo "Usage: scientific-literature-search.sh <query>"
  echo "Example: scientific-literature-search.sh 'hereditary spherocytosis osmotic fragility'"
  exit 1
fi

# Load NCBI API key if available
if [ -f .env ]; then
  source .env
fi

# Generate cache key
cache_key=$(echo -n "$query" | shasum -a 256 | awk '{print $1}')
cache_file=".claude/skills/health-agent/scientific-literature-search/.cache/${cache_key}.json"

# Check cache (30-day TTL)
if [ -f "$cache_file" ]; then
  file_age_days=$(( ($(date +%s) - $(stat -f %m "$cache_file")) / 86400 ))

  if [ $file_age_days -lt 30 ]; then
    # Format cached results as markdown
    cached_data=$(cat "$cache_file")
    echo "## Scientific Literature Search Results (Cached)"
    echo ""
    echo "**Query**: $(echo "$cached_data" | jq -r '.query')"
    echo "**Total Results**: $(echo "$cached_data" | jq -r '.total_results')"
    echo "**Fetched**: $(echo "$cached_data" | jq -r '.fetched_at') (cached, age: ${file_age_days} days)"
    echo ""
    echo "| Title | Authors | Year | Source | PMID/DOI | Citations |"
    echo "|-------|---------|------|--------|----------|-----------|"
    echo "$cached_data" | jq -r '.results[] | "| \(.title) | \(.authors) | \(.year) | \(.source) | \(if .pmid != "N/A" then "PMID:\(.pmid)" else "DOI:\(.doi)" end) | \(.citation_count // 0) |"'
    echo ""
    echo "### Abstracts (Top 5 Results)"
    echo ""
    echo "$cached_data" | jq -r '.results[:5] | .[] | "#### \(.title) (\(.year))\n\n**Authors**: \(.authors)\n**Source**: \(.source)\n**Citations**: \(.citation_count // 0)\n\n**Abstract**: \(.abstract // "N/A")\n\n**DOI**: \(.doi)\n**PMID**: \(.pmid)\n\n---\n"'
    exit 0
  fi
fi

# Query PubMed
echo "Querying PubMed..." >&2

query_encoded=$(echo "$query" | sed 's/ /+/g')
api_key_param=""
[ -n "$NCBI_API_KEY" ] && api_key_param="&api_key=$NCBI_API_KEY"

pubmed_search_url="https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=pubmed&term=${query_encoded}&retmax=10&retmode=json&sort=relevance${api_key_param}"
pubmed_ids=$(curl -s "$pubmed_search_url" | grep -oP '"idlist":\[\K[^\]]+' | tr ',' '\n' | tr -d '"')

if [ -z "$pubmed_ids" ]; then
  pubmed_results="[]"
else
  pmids=$(echo "$pubmed_ids" | head -10 | tr '\n' ',' | sed 's/,$//')
  pubmed_fetch_url="https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esummary.fcgi?db=pubmed&id=${pmids}&retmode=json${api_key_param}"
  pubmed_data=$(curl -s "$pubmed_fetch_url")

  pubmed_results=$(echo "$pubmed_data" | jq -r '
    .result
    | to_entries
    | map(select(.key != "uids"))
    | map({
        pmid: .value.uid,
        title: .value.title,
        authors: (.value.authors[:3] | map(.name) | join(", ")),
        year: (.value.pubdate[:4] // "N/A"),
        doi: (.value.articleids // [] | map(select(.idtype == "doi")) | .[0].value // "N/A"),
        citation_count: 0,
        abstract: "N/A",
        source: "PubMed"
      })
  ')
fi

# Query Semantic Scholar
echo "Querying Semantic Scholar..." >&2

ss_query_encoded=$(echo "$query" | jq -sRr @uri)
ss_search_url="https://api.semanticscholar.org/graph/v1/paper/search/bulk?query=${ss_query_encoded}&limit=10&fields=title,authors,year,abstract,citationCount,openAccessPdf,externalIds"
ss_data=$(curl -s -H "User-Agent: health-agent/1.0" "$ss_search_url")

ss_results=$(echo "$ss_data" | jq -r '
  .data
  | map({
      title: .title,
      authors: (.authors[:3] | map(.name) | join(", ")),
      year: (.year // "N/A"),
      doi: (.externalIds.DOI // "N/A"),
      pmid: (.externalIds.PubMed // "N/A"),
      citation_count: (.citationCount // 0),
      abstract: (if .abstract then (.abstract[:300] + "...") else "N/A" end),
      pdf_url: (.openAccessPdf.url // "N/A"),
      source: "Semantic Scholar"
    })
' || echo "[]")

# Merge and sort by citation count
combined_results=$(jq -s '.[0] + .[1] | sort_by(-.citation_count // 0)' <(echo "$pubmed_results") <(echo "$ss_results"))

# Create output JSON
output=$(jq -n \
  --arg query "$query" \
  --arg timestamp "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  --argjson results "$combined_results" \
  '{
    query: $query,
    fetched_at: $timestamp,
    ttl_days: 30,
    total_results: ($results | length),
    results: $results
  }')

# Save to cache
mkdir -p "$(dirname "$cache_file")"
echo "$output" > "$cache_file"

# Format as markdown
echo "## Scientific Literature Search Results"
echo ""
echo "**Query**: $query"
echo "**Total Results**: $(echo "$output" | jq -r '.total_results')"
echo "**Fetched**: $(echo "$output" | jq -r '.fetched_at')"
echo ""
echo "| Title | Authors | Year | Source | PMID/DOI | Citations |"
echo "|-------|---------|------|--------|----------|-----------|"
echo "$output" | jq -r '.results[] | "| \(.title) | \(.authors) | \(.year) | \(.source) | \(if .pmid != "N/A" then "PMID:\(.pmid)" else "DOI:\(.doi)" end) | \(.citation_count // 0) |"'
echo ""
echo "### Abstracts (Top 5 Results)"
echo ""
echo "$output" | jq -r '.results[:5] | .[] | "#### \(.title) (\(.year))\n\n**Authors**: \(.authors)\n**Source**: \(.source)\n**Citations**: \(.citation_count // 0)\n\n**Abstract**: \(.abstract // "N/A")\n\n**DOI**: \(.doi)\n**PMID**: \(.pmid)\n\n---\n"'

Usage

Direct Invocation

When user asks for scientific literature:

Copy# Save the complete script to a temporary file
cat > /tmp/scientific-literature-search.sh << 'SCRIPT_EOF'
[Complete script template from above]
SCRIPT_EOF

chmod +x /tmp/scientific-literature-search.sh

# Run with query
/tmp/scientific-literature-search.sh "hereditary spherocytosis osmotic fragility sensitivity"

From investigate-root-cause

When investigate-root-cause needs biological mechanisms:

Copy# In Phase 2 (Hypothesis Generation), replace generic WebSearch with:
/tmp/scientific-literature-search.sh "chronic hemolysis bilirubin mechanism"

# Extract PMIDs for citation
grep "PMID:" output | awk -F: '{print $2}' | tr -d ' '

Output Format

Markdown Table

Top-level summary of all results (PubMed + Semantic Scholar combined):

Copy## Scientific Literature Search Results

**Query**: hereditary spherocytosis osmotic fragility sensitivity
**Total Results**: 18
**Fetched**: 2026-01-21T12:00:00Z

| Title | Authors | Year | Source | PMID/DOI | Citations |
|-------|---------|------|--------|----------|-----------|
| Osmotic fragility test in hereditary spherocytosis | Smith J, Doe A, Brown K | 2020 | PubMed | PMID:12345678 | 45 |
| Novel diagnostic approaches for HS | Johnson M, Lee S, Wang T | 2019 | Semantic Scholar | DOI:10.1234/example | 32 |
...

Abstracts (Top 5)

Detailed abstracts for the top 5 most-cited results:

Copy### Abstracts (Top 5 Results)

#### Osmotic fragility test in hereditary spherocytosis (2020)

**Authors**: Smith J, Doe A, Brown K
**Source**: PubMed
**Citations**: 45

**Abstract**: The osmotic fragility test remains a cornerstone diagnostic tool for hereditary spherocytosis. This study evaluates sensitivity and specificity across 500 patients...

**DOI**: 10.1234/example
**PMID**: 12345678

---

Caching

Cache Structure

Copy.claude/skills/health-agent/scientific-literature-search/.cache/
├── a1b2c3d4e5f6.json  # SHA256 hash of query 1
├── f6e5d4c3b2a1.json  # SHA256 hash of query 2
└── ...

Cache File Format

Copy{
  "query": "hereditary spherocytosis osmotic fragility",
  "fetched_at": "2026-01-21T12:00:00Z",
  "ttl_days": 30,
  "total_results": 18,
  "results": [
    {
      "pmid": "12345678",
      "title": "Osmotic fragility test in HS",
      "authors": "Smith J, Doe A, Brown K",
      "year": "2020",
      "doi": "10.1234/example",
      "citation_count": 45,
      "abstract": "The osmotic fragility test...",
      "source": "PubMed"
    }
  ]
}

Cache Expiration

• TTL: 30 days
• Check: On each query, compare file modification time to current time
• Action: If age > 30 days, delete cache file and fetch fresh results
• Benefit: Balances freshness with API rate limits and performance

API Rate Limits

PubMed E-utilities

Without API key: 3 requests/second With API key: 10 requests/second

To get API key:

1. Register at https://www.ncbi.nlm.nih.gov/account/
2. Generate key in "API Key Management"
3. Add to .env: NCBI_API_KEY=your_key_here

Semantic Scholar

Unauthenticated: 1000 requests/second (shared pool) With API key: Higher limits (register at https://www.semanticscholar.org/product/api)

Current implementation: Uses unauthenticated API (sufficient for most use cases)

Error Handling

No Results Found

Copyif [ "$total_results" -eq 0 ]; then
  echo "⚠️ No results found for query: $query"
  echo ""
  echo "**Suggestions**:"
  echo "- Simplify query (remove overly specific terms)"
  echo "- Try synonyms or alternative phrasing"
  echo "- Check for typos"
  exit 0
fi

API Failures

Copy# Check if API response is valid JSON
if ! echo "$pubmed_data" | jq empty 2>/dev/null; then
  echo "❌ PubMed API error. Using Semantic Scholar results only."
  pubmed_results="[]"
fi

if ! echo "$ss_data" | jq empty 2>/dev/null; then
  echo "❌ Semantic Scholar API error. Using PubMed results only."
  ss_results="[]"
fi

Rate Limit Exceeded

Copy# PubMed returns HTTP 429 when rate limit exceeded
# Add exponential backoff:
if echo "$pubmed_data" | grep -q "429"; then
  echo "⚠️ PubMed rate limit exceeded. Waiting 2 seconds..."
  sleep 2
  # Retry once
  pubmed_data=$(curl -s "$pubmed_fetch_url")
fi

Example Invocations

User Request

User: "Find papers on hereditary spherocytosis diagnosis sensitivity"

Assistant:

Copy/tmp/scientific-literature-search.sh "hereditary spherocytosis diagnosis sensitivity"

Output: Markdown table with 15-20 papers from PubMed and Semantic Scholar

---

From investigate-root-cause

Context: Investigating chronic high bilirubin, need biological mechanism for hemolysis hypothesis

Agent action:

Copy/tmp/scientific-literature-search.sh "chronic hemolysis bilirubin unconjugated mechanism"

Usage: Extract PMIDs from results, cite in hypothesis section:

• "Hemolysis increases unconjugated bilirubin production (PMID:12345678)"

---

Pharmacogenomics Research

User: "What does research say about CYP2D6 poor metabolizers and antidepressants?"

Assistant:

Copy/tmp/scientific-literature-search.sh "CYP2D6 poor metabolizer antidepressants adverse effects"

Output: Papers on drug metabolism, dosing recommendations, adverse event rates

Integration with Other Skills

mechanism-search

mechanism-search can use this skill to find authoritative biological pathways:

Copy# Instead of generic WebSearch:
scientific-literature-search.sh "mechanism pathway $condition $observation"

investigate-root-cause

In Phase 2 (Hypothesis Generation), use for biological mechanisms:

Copy# For each hypothesis, query scientific literature:
for hypothesis in "${hypotheses[@]}"; do
  scientific-literature-search.sh "$hypothesis mechanism pathway"
done

Evidence citation in reports

Include PMIDs in hypothesis sections:

Copy**Supporting Evidence**:
1. ✅ Hemolysis increases unconjugated bilirubin (PMID:12345678)
2. ✅ Spherocytosis causes chronic hemolysis (PMID:87654321)

Maintenance

Cache Management

Caches accumulate over time. Periodically clean old entries:

Copy# Delete cache entries older than 60 days
find .claude/skills/health-agent/scientific-literature-search/.cache/ -type f -mtime +60 -delete

API Key Rotation

NCBI API keys don't expire, but can be regenerated if compromised:

1. Log into NCBI account
2. Regenerate API key
3. Update .env file
4. No code changes needed

Medical Disclaimer

This skill queries scientific literature databases for research purposes. It is not medical advice:

• Papers may have conflicting results
• Research findings require clinical context
• Always consult healthcare providers for medical decisions
• Use citations to validate hypotheses, not as diagnostic criteria