nexus-mcp-ci
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 | 60–75% |
Assess change impact (manual trace through codebase) | 10,000–20,000 tokens | 1,000–3,000 tokens via | 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 |
| ~500 tokens | Counts, scores, file:line pointers | Quick lookups, triage |
| ~2,000 tokens | Signatures, types, line ranges, docstrings | Normal development |
| ~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.
Related MCP server: embecode
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 expiration, 6 memory types, semantic recall
Explain & Impact — "What does this do?" and "What breaks if I change it?" in single tool calls
Token-budgeted responses — Three verbosity levels (summary/detailed/full) keep context windows lean
Multi-folder indexing — Index multiple directories in one call, processed folder-by-folder with shared engines
Incremental indexing — Only re-processes changed files; file watcher support
Multi-model embeddings — 2 models (jina-code default, bge-small-en), GPU/MPS auto-detection
Low memory — <350MB RAM target (ONNX Runtime ~50MB, mmap vectors, lazy model loading)
Fully local — Zero cloud dependencies, no API keys, all processing on your machine
15 tools, one server — Consolidates what previously required 2 MCP servers (17 tools) into one
Prerequisites
Python 3.10 to 3.13
pip (comes with Python)
ripgrep (rg) (optional, for 100% search coverage fallback)
Install
Option 1: pip install from PyPI (recommended)
pip install nexus-mcp-ciWith optional extras:
# With GPU (CUDA) support
pip install nexus-mcp-ci[gpu]
# With FlashRank reranker for better search quality
pip install nexus-mcp-ci[reranker]
# Both
pip install nexus-mcp-ci[gpu,reranker]Option 2: From source (for development)
git clone https://github.com/jaggernaut007/Nexus-MCP.git
cd Nexus-MCP
# Setup script (creates venv, installs, verifies)
./setup.sh
# Or manual install with dev deps
pip install -e ".[dev]"Note: The default embedding model (
jina-code) requires ONNX Runtime. This is included automatically. If you see errors about missing ONNX/Optimum, run:pip install "sentence-transformers[onnx]" "optimum[onnxruntime]>=1.19.0"To use a lighter model that doesn't need
trust_remote_code, setNEXUS_EMBEDDING_MODEL=bge-small-en.
See the full Installation Guide for all options, MCP client integration, and troubleshooting.
Run
nexus-mcpThe server starts on stdio (the default MCP transport). Point your MCP client at the nexus-mcp command.
Add to Your MCP Client
Claude Code
# Basic setup
claude mcp add nexus-mcp-ci -- nexus-mcp-ci
# With a specific embedding model
claude mcp add nexus-mcp-ci -e NEXUS_EMBEDDING_MODEL=bge-small-en -- nexus-mcp-ciTip: If you installed in a virtual environment, use the full path so the MCP client finds the right Python:
claude mcp add nexus-mcp-ci -- /path/to/Nexus-MCP/.venv/bin/nexus-mcp-ci
Claude Desktop
Add to your config file (~/Library/Application Support/Claude/claude_desktop_config.json on macOS):
{
"mcpServers": {
"nexus-mcp-ci": {
"command": "nexus-mcp-ci",
"args": []
}
}
}Cursor / Windsurf / Cline / Other MCP Clients
Add to your MCP client's server config:
{
"nexus-mcp-ci": {
"command": "nexus-mcp-ci",
"transport": "stdio"
}
}See the full Installation Guide for client-specific instructions.
MCP Tools (15)
Core
Tool | Description |
| Server status, indexing stats, memory usage, next-tool hints |
| Readiness/liveness probe (uptime, engine availability) |
| Index a codebase (full, incremental, or multi-folder) |
| Preferred over Grep/Glob. Semantic search returning code snippets, absolute paths, and scores |
Graph Analysis
Tool | Description |
| Preferred over Grep for definitions — returns location, types, and call relationships |
| Find all direct callers via call graph (more accurate than text search) |
| Trace execution flow — all functions called by a given function |
| Code complexity, dependencies, smells, and quality metrics |
| Use before refactoring. Transitive change impact analysis |
| Preferred over Read for understanding symbols — graph + vector + analysis |
| Preferred over Glob/ls. Project overview: files, languages, symbols, quality |
| Preferred over manual browsing. Layers, dependencies, entry points, hubs |
Memory
Tool | Description |
| Store a semantic memory with tags and TTL |
| Search memories by semantic similarity |
| Delete memories by ID, tags, or type |
Configuration
All settings can be overridden via NEXUS_ environment variables:
Variable | Default | Description |
|
| Storage directory for indexes |
|
| Embedding model ( |
|
| Device for embeddings: |
|
| Skip files larger than this |
|
| Max code snippet size per chunk |
|
| Memory budget |
|
| Search mode: |
|
| Vector engine weight in RRF |
|
| BM25 engine weight in RRF |
|
| Graph engine weight in RRF |
|
| Logging level |
|
| Log format: |
Self-Test Demo
Verify your installation by running the end-to-end demo that exercises all 15 tools:
python self_test/demo_mcp.py # Uses built-in sample project
python self_test/demo_mcp.py /path/to/project # Or test against your own codebaseSee self_test/README.md for details.
Development
pip install -e ".[dev]" # Install with dev deps
pytest -v # Run tests (441 tests)
pytest -m "not slow" # Skip performance benchmarks
ruff check . # Lint
nexus-mcp-ci # Run serverHow It Works
search("how does auth work")
|
|-- vector_engine.search(query, n=30) -- semantic similarity (embeddings)
|-- bm25_engine.search(query, n=30) -- keyword matching (exact terms)
|-- graph_engine.boost(query, n=30) -- structural relevance (callers/callees)
| |
| Reciprocal Rank Fusion (weights: 0.5 / 0.3 / 0.2)
| |
| FlashRank re-ranking (top 20)
| |
| Token budget truncation (summary/detailed/full)
| |
v
Top-N results, formatted to verbosity levelArchitecture
Component | Technology | Why |
Vector store | LanceDB | Disk-backed, mmap, ~20-50MB overhead, native FTS |
Embeddings | ONNX Runtime + jina-code (default) | ~50MB vs PyTorch ~500MB, GPU/MPS auto-detection, 3 models supported |
Graph engine | rustworkx | Rust-backed, O(1) node/edge lookup, PageRank, centrality |
Symbol parser | tree-sitter | 25+ languages, AST-level symbol extraction |
Graph parser | ast-grep | Structural pattern matching for calls/imports/inheritance |
Chunking | Symbol-based | One chunk per function/class, deterministic IDs |
Re-ranker | FlashRank (optional) | 4MB ONNX model, <10ms for top-20 |
Persistence | SQLite + LanceDB | Graph in SQLite, vectors in Lance, zero-config |
Documentation
Installation Guide — Prerequisites, install steps, MCP client integration, troubleshooting
Architecture — System design, data flow, components, memory budget
Usage Guide — Tool reference, configuration, best practices
Developer Guide — Setup, testing, contributing, adding tools/engines
ADRs — 11 Architecture Decision Records
Research Notes — Deep dives on libraries and technology choices
Acknowledgments
Nexus-MCP consolidates and extends two earlier projects:
CodeGrok MCP by rdondeti (Ravitez Dondeti) — Semantic code search with tree-sitter parsing, embedding service, parallel indexing, and memory retrieval. Core models, symbol extraction, and the embedding pipeline were ported from CodeGrok. Originally licensed under MIT.
code-graph-mcp by entrepeneur4lyf — Code graph analysis with ast-grep structural parsing, rustworkx graph engine, and complexity analysis. Graph models, relationship extraction, and code analysis were ported from code-graph-mcp.
Individual source files retain "Ported from" attribution in their module docstrings. See ADR-001 for the rationale behind the consolidation.
License
MIT — see LICENSE for details.
Available Tools
10 toolsanalyzeAnalyzeA
Use for code review or quality assessment — preferred over manually
reading files to eyeball complexity, since it computes cyclomatic/
cognitive complexity, dependency analysis, code smells (long/complex
functions, large classes, dead code), and an overall quality score in
one call. Read-only; requires an index (see index). Optionally scope
to a subdirectory or file via path to keep results focused and fast
on large codebases — omit it to analyze the whole indexed codebase.
| Name | Required | Description | Default |
|---|---|---|---|
| path | No | Optional relative path to filter analysis (subdirectory or file) |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and does well: it declares the operation read-only, requires an existing index, and clarifies whole-codebase behavior when path is omitted. It stops short of describing failure modes if the index is missing or stale, but this is adequate for a read-only analysis tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three dense sentences, front-loaded with the primary use case, then metrics, safety, prerequisite, and path guidance. No filler or redundant restatement of the tool name.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers purpose, what the tool computes, read-only behavior, the index prerequisite, and the one parameter's semantics, including default behavior. An output schema is present, so not describing return values is acceptable.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The schema already documents path as an optional filter, and the description adds real value: omitting path means analyzing the whole indexed codebase, while providing it keeps results focused and fast on large codebases. That goes beyond simply restating the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description names a specific resource (the indexed codebase) and enumerates concrete analyses: cyclomatic/cognitive complexity, dependency analysis, code smells, and a quality score. This is clearly distinct from siblings like status, search, or explain, which serve different purposes.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It states when to use the tool ('code review or quality assessment') and explicitly positions it as preferred over manually reading files. It also gives the prerequisite to use the index and explains how the optional path keeps analysis focused and fast, though it does not explicitly exclude sibling tools like explain or graph.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
explainExplainA
Use for onboarding to an unfamiliar symbol — combines its call-graph relationships, related code found via semantic search, and quality metrics in one call, so Read is often unnecessary. Use verbosity='summary' for a quick look, 'full' when you need everything.
| Name | Required | Description | Default |
|---|---|---|---|
| verbosity | No | Output detail level: 'summary', 'detailed', or 'full' | detailed |
| symbol_name | Yes | Name of the symbol to explain |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral disclosure burden. It communicates that this is a single aggregated call combining multiple data sources and that it can replace Read, which is meaningful behavioral context. It does not explicitly state read-only, but the nature of 'onboarding' and 'explain' makes mutation highly unlikely.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two dense sentences, no filler. The core use case is front-loaded, and the verbosity guidance is a practical addition that earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description is nearly complete for a two-parameter read-style tool with an output schema. It covers purpose, use case, an alternative tool, and parameter usage. The only notable gap is a lack of explicit routing against search/find_symbol in the provided sibling list.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds value by explaining when to use verbosity='summary' versus 'full', which goes beyond the schema's simple 'Output detail level' text. It does not add much for symbol_name, but the schema already sufficiently defines it.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific verb ('explain'), a specific resource ('an unfamiliar symbol'), and the concrete components of the result: call-graph relationships, related code via semantic search, and quality metrics. This clearly distinguishes it from sibling tools like search or find_symbol.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly says to use it for onboarding to an unfamiliar symbol and points out that Read is often unnecessary, giving clear context. However, it does not explicitly state when a sibling tool like search or find_symbol should be preferred instead.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
find_symbolFind SymbolA
Use to look up a specific function/class/symbol by name — preferred over Grep since it returns the definition plus its call-graph relationships in one call. Set exact=False for fuzzy substring matching when unsure of the exact name.
| Name | Required | Description | Default |
|---|---|---|---|
| name | Yes | Symbol name (e.g. 'create_server', 'TokenBudget') | |
| exact | No | True for exact match, False for fuzzy substring |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral disclosure burden. It discloses that the tool returns the definition plus call-graph relationships, which is valuable. However, it does not state whether the operation is read-only, whether authentication or indexing is required, or any side-effect profile. The returned data is partly covered by the output schema, but safety and prerequisites are left implicit.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is two sentences with no filler. The first sentence states purpose and advantage, the second gives parameter guidance. Every word earns its place, and the most important information is front-loaded.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple two-parameter lookup tool with an output schema present, the description covers the primary use case, the key decision about fuzzy matching, and the differentiating value over Grep. It doesn't explain prerequisites like whether an index exists, but given the tool's simplicity and the schema's completeness, this is a minor gap rather than a fail.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds a decision rule for the exact parameter: 'Set exact=False for fuzzy substring matching when unsure of the exact name.' This goes beyond the schema's mechanical descriptions to tell the agent when to change the default, adding real usage semantics.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with a specific verb+resource: 'look up a specific function/class/symbol by name'. It also differentiates from Grep by adding 'preferred over Grep since it returns the definition plus its call-graph relationships in one call', giving an agent a clear reason to choose this tool over an alternative.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description names Grep as the alternative and states the condition that makes this tool preferable. It also advises when to flip exact to false ('when unsure of the exact name'). It doesn't explicitly address other siblings like search or conditions when this tool should not be used, which keeps it from a 5, but the guidance is concrete and useful.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
graphGraphA
Use to trace who calls a function (direction='callers'), what it calls (direction='callees'), or — with transitive=True — the full transitive blast radius of changing it. MUST use transitive=True before refactoring or editing a widely-shared symbol; grep can't show transitive impact.
| Name | Required | Description | Default |
|---|---|---|---|
| direction | No | 'callers' (who calls this) or 'callees' (what this calls) | callers |
| max_depth | No | Max traversal depth when transitive=True (default 10) | |
| transitive | No | True = full transitive closure for change-impact analysis (MUST use before refactoring a shared symbol). Only valid with direction='callers'. | |
| symbol_name | Yes | Name of the function/symbol to trace |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral burden. It discloses the transitive blast-radius behavior and the critical refactoring caveat. It does not mention output format or potential cost, but the presence of an output schema and the concise warning make it adequately transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three focused sentences, each earning its place. The core behavior is stated first, then the critical warning about transitive mode, with no filler or repetition.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers the key decision drivers: what the tool does, how direction works, and when transitive mode is mandatory. Required parameters and defaults are already in the schema, and an output schema exists, so nothing essential is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds semantic value beyond the schema by framing transitive=True as necessary for change-impact analysis and explaining the conceptual blast radius. This extra context helps an agent choose parameter values correctly.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description names a specific action — tracing a function's callers or callees — and clearly distinguishes the tool from generic search or symbol lookup siblings. The direction parameter is explained inline, making the tool's purpose unmistakable.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
It explicitly says when to use the tool, when to set transitive=True, and contrasts it with grep, which cannot reveal transitive impact. This gives an agent actionable decision rules for using it before refactoring.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
healthHealthA
Use for liveness/readiness probes only (uptime, which engines are up)
— not for checking whether the index is fresh or complete; use status
for that.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the behavioral disclosure burden. It clearly defines the scope of behavior (liveness/readiness only) and what it does not cover. It does not describe side effects, but a health probe is implicitly read-only and the output schema is present.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single efficient sentence that front-loads the primary purpose and uses a dash to add the exclusion and sibling reference. Every word earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a zero-parameter liveness tool, the description provides complete selection guidance. The output schema covers return details, and the sibling list plus explicit status reference makes context complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool has zero parameters, so there is nothing for the description to explain. The schema already documents this with an empty object and additionalProperties: false, matching the baseline for parameter-free tools.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific purpose: liveness/readiness probes covering uptime and engine availability. It explicitly distinguishes itself from status, so an agent can tell them apart immediately.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives a clear when-to-use rule and an explicit exclusion: not for index freshness or completeness, with the alternative tool 'status' named. This leaves no ambiguity about routing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
indexIndexA
Use first on any new or changed codebase, before any other tool —
everything except status/health requires an index. Supports
comma-separated paths for multi-folder/monorepo indexing (processed
sequentially to keep RAM low). Incremental by default once an index
exists, and reports live progress instead of blocking silently. After
this completes, a file watcher keeps the index fresh automatically
(NEXUS_AUTO_WATCH) — re-running index manually is rarely needed.
| Name | Required | Description | Default |
|---|---|---|---|
| path | Yes | Absolute path to the codebase directory (or comma-separated paths) | |
| paths | No | Additional comma-separated paths to index |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of behavioral disclosure. It reveals incremental behavior, low-memory sequential processing, live progress reporting, and automatic file watching, all beyond what the schema provides. No behavioral aspect is hidden or contradicted.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Every sentence earns its place: prerequisite guidance, multi-folder syntax, memory rationale, incremental/progress behavior, and the watcher note. The critical 'Use first' instruction is front-loaded, and the text is dense without being bloated.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description is complete for a setup/indexing tool: it explains prerequisites, invocation timing, performance characteristics, statefulness, and automatic maintenance. Since an output schema exists, return values need not be described in prose, and the context signals show a simple 2-parameter interface.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline applies. The description reinforces that comma-separated paths are supported and adds the sequential-processing context, but it does not significantly expand on the schema's already-clear parameter descriptions. It earns a baseline 3 for not degrading clarity.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific purpose: build/refresh an index for a codebase, and explicitly frames it as the first step before almost all other tools. It distinguishes itself from siblings by noting that everything except 'status'/'health' requires an index, making its role unmistakable.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives explicit when-to-use guidance: 'Use first on any new or changed codebase, before any other tool.' It also clarifies when not to run it manually by mentioning that a file watcher automatically keeps the index fresh, and identifies the two tools ('status'/'health') that do not require indexing.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
mapMapA
PREFERRED over Glob/ls/manual browsing for project understanding. Use 'summary' for a quick project orientation, 'architecture' for design/dependency structure, 'full' for both in one call.
| Name | Required | Description | Default |
|---|---|---|---|
| detail | No | 'summary' (files/languages/quality/top-modules), 'architecture' (layers/dependencies/classes/entry points/hub symbols), or 'full' (both) | summary |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must carry the behavioral transparency burden. It conveys efficiency ('quick', 'both in one call') and scope ('project understanding'), but it does not explicitly state that the tool is read-only, whether it has side effects, or what permissions or costs might apply. The non-destructive nature is strongly implied but not stated.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three short, information-dense sentences with the preference statement front-loaded. Every sentence earns its place, and no content is unnecessarily repeated.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with one optional parameter and an output schema, invocation details are complete and the mode rules are actionable. The main gap is the lack of guidance for choosing between map and overlapping siblings such as graph or analyze, but the 'project understanding' framing covers most relevant use cases.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The single detail parameter is already fully described in the schema, so the baseline is 3. The description adds task-oriented meaning by mapping each value to a use case ('quick project orientation', 'design/dependency structure') and by noting the efficiency of full in one call, which goes slightly beyond the schema's field listing.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description clearly identifies map as the tool for project understanding, with summary, architecture, and full modes. It does not state an explicit verb+resource like 'Generate a project map', and it does not distinguish itself from siblings such as graph or analyze, but it is far from vague or tautological.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description explicitly says map is PREFERRED over Glob/ls/manual browsing for project understanding and gives precise mode-selection rules: summary for quick orientation, architecture for design/dependency structure, full for both. This is clear when-to-use guidance with named alternatives.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
memoryMemoryA
Persist and retrieve project context across sessions. Use action='store' to save a decision/note, action='search' to find memories by semantic similarity, action='delete' to clean up by ID, tags, or type.
| Name | Required | Description | Default |
|---|---|---|---|
| ttl | No | Time-to-live for action='store': 'permanent', 'month', 'week', 'day', 'session' | permanent |
| tags | No | Comma-separated tags (all actions) | |
| limit | No | Max results (action='search', default 5) | |
| query | No | Natural language search query (action='search') | |
| action | Yes | 'store' (was remember), 'search' (was recall), or 'delete' (was forget) | |
| content | No | Memory content to store (action='store') | |
| project | No | Project name for scoping (action='store') | default |
| memory_id | No | Specific memory ID to delete (action='delete') | |
| memory_type | No | Type/filter, e.g. 'note', 'decision' (store: type; search/delete: filter) |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It discloses cross-session persistence, semantic-similarity search, and destructive cleanup behavior. It could mention irreversible deletion or TTL expiry more explicitly, but the core behavioral traits are visible.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Two sentences with no filler. The primary purpose is front-loaded, and the action mappings are compact and scannable. Every clause earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a tool with nine parameters and no annotations, the description covers the essential decision points: which action to select and what each action accomplishes. The output schema exists and the parameter schema covers the remaining details, so the description is sufficiently complete for correct invocation.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents all nine parameters. The description adds conceptual grouping around actions but does not provide additional parameter-level detail beyond what the schema states, which is exactly the baseline-3 scenario.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description opens with a clear verb-resource pair: 'Persist and retrieve project context across sessions.' It then enumerates three concrete actions (store, search, delete), each tied to a specific purpose, so an agent can distinguish this memory tool from generic siblings like search and status.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description tells the agent exactly when to use each action: save a decision/note, find memories by semantic similarity, or clean up by ID/tags/type. It lacks explicit exclusions or comparisons to sibling tools, so it is clear but does not fully meet the 'when-not and alternatives' bar.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
searchSearchA
Use for any "where is/how does/find" code question — preferred over
Grep/Glob, and usually answerable from the returned code_snippet without
a follow-up Read. Falls back to live grep automatically when hybrid
results are sparse. Returns a non-null warning if the index looked
stale (a background reindex is triggered; results still return now).
| Name | Required | Description | Default |
|---|---|---|---|
| mode | No | Search mode: 'hybrid', 'vector', or 'bm25' | hybrid |
| limit | No | Max results (default 10, max 100) | |
| query | Yes | Natural language or code query (e.g. 'retry logic') | |
| rerank | No | FlashRank reranking (default True) | |
| language | No | Filter by language (e.g. 'python') | |
| live_grep | No | Force live-grep fallback (rg/grep) | |
| symbol_type | No | Filter by type (e.g. 'function', 'class') |
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full behavioral burden, and it delivers meaningful context: automatic fallback to live grep, stale-index warning semantics, background reindex triggering, and results still returning. It does not cover read-only/safety explicitly, but for a search tool this is substantial disclosure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
Three dense, purposeful sentences with no filler. The primary use case and preference guidance are front-loaded, followed by behavior and warning semantics — every sentence earns its place.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description covers when to use the tool, fallback behavior, and warning semantics, and an output schema exists to document return values. It is slightly short on how mode/rerank/grep parameters interact with the described fallback, but overall an agent has enough context to invoke it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the schema already documents all seven parameters. The description adds contextual value by mentioning 'hybrid results', 'code_snippet', and 'warning', but it does not explain parameter meanings beyond the schema, so the baseline 3 is appropriate.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific use case ('where is/how does/find code question') and names the preferred alternative (Grep/Glob), making the tool's purpose and differentiation clear. It also signals that results are often self-sufficient via 'code_snippet', so an agent knows what this tool is for and what it returns.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
Explicitly tells the agent when to use this tool versus Grep/Glob and notes the automatic live-grep fallback. It does not explicitly contrast with sibling tools like find_symbol or graph, but the stated query-type guidance is strong enough to route most calls correctly.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
statusStatusA
Use at the start of a session, or when unsure if search results might be stale. Reports whether a codebase is indexed, index size/engine availability, memory usage, and a stale/staleness_warning pair if files changed since the last index (a background reindex is auto-triggered).
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Output Schema
| Name | Required | Description |
|---|---|---|
No output parameters | ||
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It explains what the tool reports and discloses that a background reindex is auto-triggered when files change, which is a meaningful side-effect an agent should know about.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single, front-loaded sentence that starts with the key usage guidance and then enumerates the reported fields. Every clause earns its place; there is no redundancy or filler.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The tool has no parameters and an output schema, so the description need not explain return values in depth. It covers purpose, usage timing, reported metrics, staleness behavior, and the auto-reindex side effect, making it complete for an agent to decide when and why to call it.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
The tool has zero parameters, so parameter semantics are not applicable. The baseline for zero-parameter tools is 4, and the description appropriately focuses on behavior rather than parameter details.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description states a specific action ('Reports') and a precise resource scope: codebase index status, including index size, engine availability, memory usage, and staleness information. It clearly distinguishes itself from sibling tools like search and index by centering on index health and staleness.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The description gives explicit when-to-use guidance: at the start of a session or when search results might be stale. It does not name alternative tools explicitly, but the use cases are clear enough to guide an agent away from search or index tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
3 tool updates
- Added
graph - Added
search - Added
status
7 tool updates
v1.0.4- First observed
analyze - First observed
explain - First observed
find_symbol - First observed
health - First observed
index - First observed
map - First observed
memory
TDQS
Scored across 10 tools
Each tool has a clearly distinct responsibility: index/status/health manage the index lifecycle, map/search/find_symbol/graph/explain serve different code-comprehension needs, analyze covers quality, and memory handles persistent context. Even the potentially overlapping status/health pair is explicitly differentiated by freshness vs liveness.
Tool names are consistently lowercase and concise, mostly single imperative verbs. The pattern is slightly uneven because find_symbol uses verb_noun and memory is a noun rather than an action, but there are no mixed casing conventions or vague generic names.
Ten tools is well within the ideal scope for a code-intelligence server. Each tool covers a meaningful capability without redundancy, and the count feels neither thin nor bloated.
The set covers the full workflow of indexing, monitoring, searching, navigating, analyzing, explaining, and retaining project context. Minor gaps exist—there is no explicit unindex/forget tool or a way to list all indexed codebases—but core workflows have no dead ends.
Maintenance
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Persistent memory and cross-session learning for AI coding assistants (hosted remote MCP).
Multiple MCP tools, persistent graph memory, token-saving data pointers, and more.
An MCP server that gives your AI access to the source code and docs of all public github repos
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