Unified MCP server with hybrid search, code graph, and semantic memory.
Nexus-MCP
The only MCP server with hybrid search + code graph + semantic memory — fully local.
Nexus-MCP is a unified, local-first code intelligence server built for the Model Context Protocol. It combines vector search, BM25 keyword search, and structural graph analysis into a single process — giving AI agents precise, token-efficient code understanding without cloud dependencies.
Why Nexus-MCP?
AI coding agents waste tokens. A lot of them. Every time an agent reads full files to find a function, grep-searches for keywords that miss semantic intent, or makes multiple tool calls across disconnected servers — tokens burn. Nexus-MCP fixes this.
Token Efficiency: The Numbers
| Scenario | Without Nexus | With Nexus | Savings |
|---|---|---|---|
| Find relevant code (agent reads 5-10 files manually) | 5,000–15,000 tokens | 500–2,000 tokens (summary mode) | 70–90% |
| Understand a symbol (grep + read file + read callers) | 3,000–8,000 tokens across 3-5 tool calls | 800–2,000 tokens in 1 explain call |
60–75% |
| Assess change impact (manual trace through codebase) | 10,000–20,000 tokens | 1,000–3,000 tokens via impact tool |
80–85% |
| Tool descriptions in context (2 separate MCP servers) | ~1,700 tokens (17 tools) | ~1,000 tokens (15 consolidated) | 40% |
| Search precision (keyword-only misses, needs retries) | 2–3 searches × 2,000 tokens | 1 hybrid search × 1,500 tokens | 60–75% |
Estimated savings per coding session: 15,000–40,000 tokens (30–60% reduction) compared to standalone agentic file browsing.
Three Verbosity Levels
Every tool respects a token budget — agents request only the detail they need:
| Level | Budget | What's Returned | Use Case |
|---|---|---|---|
summary |
~500 tokens | Counts, scores, file:line pointers | Quick lookups, triage |
detailed |
~2,000 tokens | Signatures, types, line ranges, docstrings | Normal development |
full |
~8,000 tokens | Full code snippets, relationships, metadata | Deep analysis |
vs. Standalone Agentic Development (No Code MCP)
Without a code intelligence server, AI agents must:
- Read entire files to find one function (~500–2,000 tokens/file, often 5–10 files per query)
- Grep for keywords that miss semantic intent ("auth" won't find "verify_credentials")
- Manually trace call chains by reading file after file
- Lose all context between sessions — no persistent memory
Nexus-MCP replaces this with targeted retrieval: semantic search returns the exact chunks needed, graph queries trace relationships instantly, and memory persists across sessions.
vs. Competitor MCP Servers
| Feature | Nexus-MCP | Sourcegraph MCP | Greptile MCP | GitHub MCP | tree-sitter MCP |
|---|---|---|---|---|---|
| Local / private | Yes | No (infra required) | No (cloud) | No (cloud) | Yes |
| Semantic search | Yes (embeddings) | No (keyword) | Yes (LLM-based) | No (keyword) | No |
| Keyword search | Yes (BM25) | Yes | N/A | Yes | No |
| Hybrid fusion | Yes (RRF) | No | No | No | No |
| Code graph | Yes (rustworkx) | Yes (SCIP) | No | No | No |
| Re-ranking | Yes (FlashRank) | No | N/A | No | No |
| Semantic memory | Yes (6 types) | No | No | No | No |
| Change impact | Yes | Partial | No | No | No |
| Token budgeting | Yes (3 levels) | No | No | No | No |
| Languages | 25+ | 30+ | Many | Many | Many |
| Cost | Free | $$$ | $40/mo | $10–39/mo | Free |
| API keys needed | No | Yes | Yes | Yes | No |
vs. AI Code Tools (Cursor, Copilot, Cody, etc.)
| Capability | Nexus-MCP | Cursor | Copilot @workspace | Sourcegraph Cody | Continue.dev | Aider |
|---|---|---|---|---|---|---|
| IDE-agnostic | Yes | No | No | No | No | Yes |
| MCP-native | Yes | Partial | No | No | Yes (client) | No |
| Fully local | Yes | Partial | No | Partial | Yes | Yes |
| Hybrid search | Yes | Unknown | Unknown | Keyword | Yes | No |
| Code graph | Yes | Unknown | Unknown | Yes (SCIP) | Basic | No |
| Semantic memory | Yes (persistent) | No | No | No | No | No |
| Token-budgeted responses | Yes | N/A | N/A | N/A | N/A | N/A |
| Open source | Yes (MIT) | No | No | Partial | Yes | Yes |
| Cost | Free | $20–40/mo | $10–39/mo | $0–49/mo | Free | Free |
Nexus-MCP's unique combination: No other tool delivers hybrid search + code graph + semantic memory + token budgeting + full privacy in a single MCP server.
Key Features
- Hybrid search — Vector (semantic) + BM25 (keyword) + graph (structural) fused via Reciprocal Rank Fusion, then re-ranked with FlashRank
- Code graph — Structural analysis via rustworkx: callers, callees, imports, inheritance, change impact
- Dual parsing — tree-sitter (symbol extraction) + ast-grep (structural relationships), 25+ languages
- Semantic memory — Persistent knowledge store with TTL e
Tools (3)
explainProvides a detailed explanation of a symbol or code block.impactAssesses the potential impact of changes within the codebase.searchPerforms hybrid search using vector, BM25, and graph analysis.Configuration
{"mcpServers": {"nexus-mcp": {"command": "npx", "args": ["-y", "nexus-mcp"]}}}