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hybrid-search-implementation

wshobson/agents

Combine vector and keyword search for better retrieval in RAG and search systems.

What is hybrid-search-implementation?

Hybrid search merges semantic vector similarity with exact keyword matching to improve recall and handle domain-specific queries. Use this when building RAG systems, search engines, or when either approach alone misses relevant results.

  • Fuse vector search and keyword search results using multiple strategies (RRF, linear weighting, cross-encoder reranking, cascade filtering)
  • Handle queries with specific terms, names, and codes that pure vector search may miss
  • Improve semantic understanding while preserving exact matching capabilities
  • Rerank combined results for higher quality output
  • Log and debug both vector and keyword scores for optimization

How to install hybrid-search-implementation

npx skills add https://github.com/wshobson/agents --skill hybrid-search-implementation
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How to use hybrid-search-implementation

  1. 1.Choose a fusion method (RRF for simplicity, linear for tuning, cross-encoder for quality, cascade for efficiency)
  2. 2.Implement vector search and keyword search components in parallel
  3. 3.Apply fusion logic to combine and rank results from both approaches
  4. 4.Add reranking with a cross-encoder model for significant quality improvement
  5. 5.Test weights empirically on your data and A/B test with real users

Use cases

Good for
  • Building RAG systems with improved recall for domain-specific documents
  • Implementing search engines that need both semantic and exact-match capabilities
  • Handling technical queries with specific codes, product names, or identifiers
  • Improving search quality when pure vector embeddings miss keyword-relevant results
  • Tuning search behavior for different query types in production systems
Who it's for
  • RAG system builders
  • Search engine developers
  • ML engineers optimizing retrieval pipelines
  • Teams handling domain-specific vocabulary and technical terminology

hybrid-search-implementation FAQ

Which fusion method should I start with?

Start with Reciprocal Rank Fusion (RRF) - it works well without tuning and doesn't require weight configuration.

Do I need both vector and keyword search?

Yes. Keyword search handles exact matches and domain-specific terms better, while vector search captures semantic meaning. Together they improve recall significantly.

How do I tune the balance between vector and keyword results?

Test empirically on your data. Use linear weighting to adjust the balance, or use RRF for a parameter-free approach. A/B test with real users to measure impact.

Should I rerank the fused results?

Yes. Adding a cross-encoder reranking step provides significant quality improvement and is a best practice for production systems.

What should I do if I get empty results?

Handle edge cases explicitly - consider fallback strategies like expanding keyword queries, lowering similarity thresholds, or returning partial results.

Full instructions (SKILL.md)

Source of truth, from wshobson/agents.


name: hybrid-search-implementation description: Combine vector and keyword search for improved retrieval. Use when implementing RAG systems, building search engines, or when neither approach alone provides sufficient recall.

Hybrid Search Implementation

Patterns for combining vector similarity and keyword-based search.

When to Use This Skill

  • Building RAG systems with improved recall
  • Combining semantic understanding with exact matching
  • Handling queries with specific terms (names, codes)
  • Improving search for domain-specific vocabulary
  • When pure vector search misses keyword matches

Core Concepts

1. Hybrid Search Architecture

Query → ┬─► Vector Search ──► Candidates ─┐
        │                                  │
        └─► Keyword Search ─► Candidates ─┴─► Fusion ─► Results

2. Fusion Methods

MethodDescriptionBest For
RRFReciprocal Rank FusionGeneral purpose
LinearWeighted sum of scoresTunable balance
Cross-encoderRerank with neural modelHighest quality
CascadeFilter then rerankEfficiency

Templates and detailed worked examples

Full template library and detailed worked examples live in references/details.md. Read that file when you need the concrete templates.

Best Practices

Do's

  • Tune weights empirically - Test on your data
  • Use RRF for simplicity - Works well without tuning
  • Add reranking - Significant quality improvement
  • Log both scores - Helps with debugging
  • A/B test - Measure real user impact

Don'ts

  • Don't assume one size fits all - Different queries need different weights
  • Don't skip keyword search - Handles exact matches better
  • Don't over-fetch - Balance recall vs latency
  • Don't ignore edge cases - Empty results, single word queries