VecGrep

Cursor-style semantic code search as an MCP plugin for Claude Code.

Instead of grepping 50 files and sending 30,000 tokens to Claude, VecGrep returns the top 8 semantically relevant code chunks (~1,600 tokens). That's a ~95% token reduction for codebase queries.

Benchmarks

Measured on the VecGrep codebase itself (5 source files, ~26k tokens raw).

Token usage per query

search_graph returns structured node metadata only (name, kind, file, line range) — no source code — so it's ultra-cheap for structural questions ("where is X defined?", "what calls Y?").

Query latency (median, 5 runs)

search_graph is ~30× faster than vector search — pure in-memory graph traversal, no embedding model call.

Result correctness (structural queries)

For name-based structural queries, pure vector search can rank documentation (CHANGELOG, README) above source code. The graph index fixes this:

The graph score (graph_score: 1.00) overrides a misleading vector match whenever the query directly names a known symbol.

Rule of thumb: use search_code for semantic/behaviour queries, search_graph for structural/navigation queries, hybrid_search when you need both.

Related MCP server: mcplens

How it works

1. Chunk — Parses source files with tree-sitter to extract semantic units (functions, classes, methods)

2. Embed — Encodes each chunk using the configured embedding provider:

   • Local (default) — all-MiniLM-L6-v2-code-search-512 via fastembed ONNX (~100ms startup, no API key) or PyTorch, with auto device detection (Apple Silicon, CUDA, CPU)

   • Cloud (BYOK) — OpenAI, Voyage AI, or Google Gemini via your own API key (higher-quality embeddings, optional)

3. Store — Saves embeddings + metadata in LanceDB under ~/.vecgrep/<project_hash>/; vector dimensions adapt automatically to the chosen provider

4. Search — ANN index (IVF-PQ) for fast approximate search on large codebases

Incremental re-indexing via mtime/size checks skips unchanged files.

Architecture

Installation

Requires Python 3.12 and uv.

Note: Python 3.12 is required — tree-sitter-languages does not yet have wheels for Python 3.13+.

pip install vecgrep                        # standard pip
uv tool install --python 3.12 vecgrep     # uv tool (recommended)

Claude Code integration

Run once — works for every project:

claude mcp add --scope user vecgrep -- vecgrep

This installs VecGrep as a persistent binary and registers it in your user config (~/.claude.json) so it's available globally across all projects. Starts instantly — no download delay on Claude Code launch.

Usage with Claude

You don't trigger VecGrep manually - Claude decides when to call the tools based on what you ask.

Typical first-time flow:

You:    "Search for how payments are handled in /Users/me/myapp"
Claude: [calls index_codebase automatically since no index exists]
Claude: [calls search_code with your query]
Claude: "Here's how payments work — in src/payments.py:42..."

After the first index, subsequent searches skip unchanged files automatically — no re-indexing needed unless your code changes.

Tools

index_codebase(path, force=False, watch=False, provider=None)

Index a project directory. Skips unchanged files on subsequent calls.

index_codebase("/path/to/myproject")
# → "Indexed 142 file(s), 1847 chunk(s) added (0 file(s) skipped, unchanged)"

# Use OpenAI embeddings instead of local
index_codebase("/path/to/myproject", provider="openai")

Provider lock: once a project is indexed with a provider, re-indexing with a different provider requires force=True (this rebuilds the vector table with the new embedding dimensions).

Note: watch=True is only supported with the local provider — live sync with cloud providers would incur unbounded API costs.

search_code(query, path, top_k=8)

Semantic search. Auto-indexes if no index exists.

search_code("how does user authentication work", "/path/to/myproject")

Returns formatted snippets with file paths, line numbers, and similarity scores:

[1] src/auth.py:45-72 (score: 0.87)
def authenticate_user(token: str) -> User:
    ...

[2] src/middleware.py:12-28 (score: 0.81)
...

get_index_status(path)

Check index statistics, including the embedding provider used.

Index status for: /path/to/myproject
  Files indexed:  142
  Total chunks:   1847
  Last indexed:   2026-02-22T07:20:31+00:00
  Index size:     28.4 MB
  Provider:       local
  Model:          isuruwijesiri/all-MiniLM-L6-v2-code-search-512
  Dimensions:     384

index_graph(path, force=False)

Build a structural knowledge graph from the codebase using tree-sitter AST extraction. No LLM required — extracts files, functions, classes, and methods as nodes; contains, calls, imports, and inherits as directed edges. Independent of the vector index.

index_graph("/path/to/myproject")
# → "Graph built: 496 nodes, 1251 edges, 35 files processed."

search_graph(query, path, limit=20)

Keyword search over node labels (function names, class names, file names). Returns structural nodes with source location and connectivity degree. Ultra-cheap: ~47 tokens average, ~3ms latency.

search_graph("VectorStore", "/path/to/myproject")
# → [1] CLASS  VectorStore  (score: 1.00, degree: 39)
#       src/vecgrep/store.py:49-352

graph_neighbors(node_id, path, depth=1)

Return the structural neighbourhood of any node — callers, callees, imports, contained methods, and inheritance edges. Use search_graph first to find the node ID.

graph_neighbors("VectorStore", "/path/to/myproject", depth=1)
# → Callers (18): _get_store, migrate_project, test fixtures...
#   Contains (18): search, add_chunks, replace_file_chunks...

hybrid_search(query, path, top_k=8, alpha=0.6, min_score=0.0)

Vector similarity search re-ranked by graph proximity. Final score = alpha * vector_score + (1 - alpha) * graph_score. Fixes cases where documentation ranks above source code on pure embedding similarity.

hybrid_search("VectorStore search method", "/path/to/myproject", alpha=0.6)
# → [1] src/vecgrep/store.py:292-320 (blended: 0.70, vec: 0.49, graph: 1.00)

Requires both index_codebase and index_graph to have been run. Degrades gracefully to pure vector search if the graph index is absent.

Configuration

VecGrep can be tuned via environment variables:

Local provider

Backend comparison:

Cloud providers (BYOK — Bring Your Own Key)

VecGrep supports three cloud embedding providers. Each requires an API key environment variable and the corresponding optional dependency.

Install cloud extras:

# Single provider
uv tool install --python 3.12 'vecgrep[openai]'
pip install 'vecgrep[openai]'

# All cloud providers at once
pip install 'vecgrep[cloud]'

Use a cloud provider:

# Set your API key
export VECGREP_OPENAI_KEY=sk-...

# Index with OpenAI embeddings
index_codebase("/path/to/myproject", provider="openai")

# Or tell Claude to use it:
# "Index my project at /path/to/myproject using openai embeddings"

Switch providers (requires force re-index to rebuild the vector table):

index_codebase("/path/to/myproject", provider="voyage", force=True)

Local backend examples:

# Use a different model with the torch backend
VECGREP_BACKEND=torch VECGREP_MODEL=sentence-transformers/all-MiniLM-L6-v2 vecgrep

# Use a custom ONNX model
VECGREP_MODEL=my-org/my-onnx-model vecgrep

Supported languages

Python, JavaScript/TypeScript, Rust, Go, Java, C/C++, Ruby, Swift, Kotlin, C#

All other text files fall back to sliding-window line chunks.

Index location

~/.vecgrep/<sha256-of-project-path>/index.db

Each project gets its own isolated index. Delete the directory to wipe the index.

Acknowledgements

The embedding model used by VecGrep is all-MiniLM-L6-v2-code-search-512, a model fine-tuned specifically for semantic code search by @isuruwijesiri.

@misc{all_MiniLM_L6_v2_code_search_512,
  author    = {isuruwijesiri},
  title     = {all-MiniLM-L6-v2-code-search-512},
  year      = {2026},
  publisher = {Hugging Face},
  url       = {https://huggingface.co/isuruwijesiri/all-MiniLM-L6-v2-code-search-512}
}

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