anyindex-mcp

Fully local MCP server for indexing a codebase and answering semantic search queries about it. No external API calls, no telemetry, no server process to run.

• AST-aware chunking via tree-sitter — chunks follow function and class boundaries, never cut mid-statement

• Offline embeddings via ONNX in-process; after the first download the model works with no network

• Hybrid search — vector + BM25 fused with RRF

• One SQLite file in the project, plus an FTS5 index

• Works on Windows without Visual Studio Build Tools — see Platform

Quickstart

Wire it into a client — nothing to install, see Client configuration:

npx --package anyindex-mcp anyindex-mcp-server

Build the index once from your project, so the first search has something to read:

npx --package anyindex-mcp anyindex-mcp reindex --root /path/to/project
npx --package anyindex-mcp anyindex-mcp search --root /path/to/project "user authentication flow"

After a global npm install -g anyindex-mcp the npx --package … prefix drops away and the commands are just anyindex-mcp reindex and anyindex-mcp search.

A second reindex only touches changed files. To keep the index fresh while you edit, pass --watch to the server, not to the CLI:

npx --package anyindex-mcp anyindex-mcp-server --watch

To work on anyindex-mcp itself, from a checkout:

npm install
npm run build
npm run probe      # environment check, prints ms/chunk

Related MCP server: semantic-search-mcp

Requirements

Node ^22.19.0 || >=24.0.0. Node 23.x does not qualify at any patch level.

Embedding dominates the wall clock: plan against ~1 s/chunk on 4 cores, not the optimistic probe figure. If a run stalls, it is memory pressure — free RAM and retry. Measured numbers in docs/06-environment.md §14.

Install

To use it as an MCP server, install nothing. Every client below runs the package through npx, which downloads it on first start and caches it:

npx --package anyindex-mcp anyindex-mcp-server

To use the command line from any project, either prefix each call the same way or install it once:

npm install -g anyindex-mcp
anyindex-mcp --version

npm install -g needs elevated rights on some Windows setups. The npx form works everywhere and is otherwise identical.

To work on anyindex-mcp itself, from a checkout:

npm install
npm run build
npm run probe      # environment check, prints ms/chunk

probe checks Node version, sqlite-vec, code-chunk, the embedding model, and write permissions, and prints throughput numbers. Exit code 1 means a blocking failure — the stack should be reconsidered before writing code.

The package also installs as a dependency and puts both executables on your path. Checked from a tarball into an empty project, with npm's install scripts blocked:

npm install ./anyindex-mcp-1.0.1.tgz
npx anyindex-mcp help

Usage

Search output looks like this:

1. src/auth/login.ts:14-24  loginUser  distance 0.957 (moderate)
   export async function loginUser(email: string, password: string) {
     const row = await db.query('select * from users where email = ?', [email])
     ...

Running as an MCP server

The server speaks MCP over stdio. Nothing is written to stdout except JSON-RPC framing; all diagnostics go to stderr, so the channel stays clean. It takes no arguments and needs no configuration file.

npx --package anyindex-mcp anyindex-mcp-server

Wire it into a client as described below.

Command-line reference

anyindex-mcp reindex --root /path/to/project   # build the index
anyindex-mcp update  --root /path/to/project   # incremental
anyindex-mcp status  --root /path/to/project   # state, --json for machine output
anyindex-mcp search  --root /path/to/project "user authentication flow"
anyindex-mcp probe                           # environment and hardware
anyindex-mcp benchmark                        # quality benchmark
anyindex-mcp --version                        # package version
anyindex-mcp help                            # same as --help

reindex and update exit 1 if --root does not exist. Without that check a mistyped path scans nothing and reports a finished reindex.

search supports --mode semantic|keyword|hybrid, --topK, and --json; --help prints usage. Exit code is 1 when the index is not ready, so shell scripts can branch on it. Search refuses to run against an unready index rather than returning plausible-looking results.

topK counts files, not chunks: one file never takes two slots, so you may get fewer results than you asked for.

Client configuration

Every client runs the same command and differs only in the config file it reads. All of them run the package through npx, so there is nothing to install first:

command: npx
args:    -y --package anyindex-mcp anyindex-mcp-server
env:     ANYINDEX_LOG_LEVEL=warn   (optional)

--package is load-bearing. npx resolves a package name, not a binary name, and this package ships two binaries — anyindex-mcp (the CLI) and anyindex-mcp-server (the MCP server). Writing npx -y anyindex-mcp-server resolves nothing:

npm error could not determine executable to run

claude mcp add writes the entry for you. Everything after -- goes to the server untouched, which is what keeps -y from being read as Claude Code's own flag:

claude mcp add anyindex-mcp -- npx -y --package anyindex-mcp anyindex-mcp-server

The same entry by hand in .mcp.json at the project root:

{
  "mcpServers": {
    "anyindex-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "--package", "anyindex-mcp", "anyindex-mcp-server"],
      "env": { "ANYINDEX_LOG_LEVEL": "warn" }
    }
  }
}

~/.cursor/mcp.json for every project, .cursor/mcp.json for one, or Settings → Customize → MCP to add it through the UI.

{
  "mcpServers": {
    "anyindex-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "--package", "anyindex-mcp", "anyindex-mcp-server"]
    }
  }
}

.vscode/mcp.json in a project, or the user-profile mcp.json from the MCP: Open User Configuration command — servers go under a top-level servers object there:

{
  "servers": {
    "anyindex-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "--package", "anyindex-mcp", "anyindex-mcp-server"]
    }
  }
}

The portable alternative is .mcp.json at the project root, which other clients read too, under mcpServers:

{
  "mcpServers": {
    "anyindex-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "--package", "anyindex-mcp", "anyindex-mcp-server"]
    }
  }
}

Claude → Settings → Developer → Edit Config.

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "anyindex-mcp": {
      "command": "npx",
      "args": ["-y", "--package", "anyindex-mcp", "anyindex-mcp-server"]
    }
  }
}

Claude Desktop has no working directory of its own, so it launches the server from its own config directory. See which folder gets indexed below — for Desktop, --root is the one thing worth setting.

Quit and restart Claude Desktop: it reads the file at launch, not on change.

Settings → AI → MCP Servers → Add Local Server, or open the settings file directly (zed: open settings file). Zed's key is context_servers:

{
  "context_servers": {
    "anyindex-mcp": {
      "command": "npx",
      "args": ["-y", "--package", "anyindex-mcp", "anyindex-mcp-server"],
      "env": {}
    }
  }
}

mcp.<name>.command is an array here, not a string, and there is a separate cwd. The schema is validated at startup and rejects unknown fields.

Project config: ./opencode.json, ./opencode.jsonc or .opencode/opencode.json at the repository root. The configuration is read once at startup and is not reloaded — restart opencode after an edit.

{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "anyindex-mcp": {
      "type": "local",
      "command": ["npx", "-y", "--package", "anyindex-mcp", "anyindex-mcp-server"],
      "cwd": ".",
      "environment": { "ANYINDEX_LOG_LEVEL": "warn" },
      "enabled": true,
      "timeout": 120000
    }
  }
}

timeout matters: the first anyindex_search loads the model into a worker and took 2745 ms on a warm index, against 145 ms for the next call. opencode defaults to 5000 ms, which is enough — a client with a shorter timeout drops the first call while everything is actually working.

Almost every MCP client reads a stdio server the same way:

command: npx
args:    -y --package anyindex-mcp anyindex-mcp-server
env:     ANYINDEX_ROOT=/absolute/path   (optional, see below)

On Windows, use npx.cmd if your client cannot launch npx through a shell. It takes no arguments, needs no API key, and writes its log to stderr, so stdout carries nothing but JSON-RPC.

To confirm a client started it correctly, call ping — it reports the resolved configuration rather than just answering. See docs/10-clients.md for per-client notes and what has and has not been verified.

Which folder gets indexed

No project path is required in the config. The working folder is taken from wherever the agent was started, resolved up to the nearest enclosing repository root. Start the agent in ~/work/myrepo/src/api and it indexes ~/work/myrepo, not the subdirectory. Outside a repository it uses the working directory as it stands.

That also means the server has to be started from the project. A client that spawns MCP servers from its own config directory rather than the project would resolve the wrong root; ping reports the root it actually chose, so this is one call to check:

{ "echo": "pong", "root": "/home/you/work/myrepo", "model": "jinaai/jina-embeddings-v2-base-code",
  "node": "v24.21.0", "index": "/home/you/work/myrepo/.anyindex/index.db",
  "models": "/home/you/.cache/anyindex-mcp/models" }

To pin the folder regardless of where the client starts from, set ANYINDEX_ROOT in env to an absolute path.

Before the first search

A fresh install has no index. Until one is built, anyindex_search refuses to answer rather than returning plausible-looking results, and index_status says so. Build it once, from the project:

npx --package anyindex-mcp anyindex-mcp reindex --root .

After that a second reindex only touches changed files.

Configuration

All settings are optional. The server reads flags first, then environment variables, then defaults.

Chunking and batching internals (chunkSizeBytes, maxFileBytes, batchSize) are fixed in src/config.ts and intentionally not exposed as flags or environment variables.

Only the index goes into the project: .anyindex/ holds the database and nothing else. The model is ~157 MB, identical for every project on the machine, so it is downloaded once into the user cache — <root> stays clean, and deleting node_modules does not throw it away. Point --models elsewhere to share one cache between accounts or to keep it on a different volume.

No API keys. The embedding model is Apache-2.0 and ungated, so nothing secret is ever configured — which also means there are no *_TOKEN-style variables for MCP clients to strip from subprocess environments.

The model is fetched from Hugging Face on first use, not by npm install, and lands in the user cache. After that first download nothing reaches the network, so --offline works from a warm cache and fails with a clear error from a cold one.

Ignored files

Ignore rules follow git's own precedence, verified against git check-ignore:

Nested ignore files are honoured: src/.gitignore applies to src/, and a deeper file overrides a shallower one, including re-including a path with !. node_modules/ and .git/ are excluded programmatically and cannot be re-enabled by any rule. Paths are relative to --root.

Tools

Parameters:

index_update and index_rebuild return immediately and work in the background, so the client's request timeout does not limit indexing. Poll index_status until running is false.

The timeout does matter for anyindex_search: the first call loads the model and takes seconds. Measured 2745 ms on a warm model, then 145 ms and 119 ms.

anyindex_search refuses to run when index_status reports the index unready or degraded, rather than returning weaker results that look normal. A half-vectorized index counts as degraded: index_rebuild is the fix. Per-client wiring and timeouts are in the client notes; see ADR-010 for why the refusal exists.

Measured quality

The indexer, hybrid search and watcher work end to end. 118 tests pass. Verified on Linux x64, Windows x64 and macOS x64 — CI runs the build, the type check and the test suite on all three, on Node 22.19 and 24, plus probe on each.

Retrieval quality was measured on 520 questions mined from commit history in Flask, Gson and Fastify, against a grep baseline charged with the same tokenizer: the correct file reaches the top 3 in 0.531 of cases versus 0.110 for grep, at 1080 context tokens per question versus 3800.

Two limits are measured and unfixed:

• Russian queries retrieve roughly 0.2 further than English ones. A multilingual model scores the same, so this is a property of matching Russian against English code, not of the model.

• No relevance threshold exists — across three models the distance gap between the worst positive and best negative case is negative. Results carry a distance and a confidence label instead of being silently filtered.

Quality also falls as the corpus grows, which is currently the largest measured limit: top-3 is 0.711 on Flask, 0.473 on Gson, 0.328 on Fastify. Benchmark, per-language numbers and the failure analysis are in docs/06-environment.md §18.

Platform

Target platform is Windows (ADR-011). Rules that follow from it:

• Native modules ship a prebuilt binary inside the package; no Visual Studio Build Tools are needed

• Paths are normalized to POSIX separators before storage, so an index built on Windows opens on Linux and back

• A .cmd wrapper is installed alongside the POSIX entry point

• chokidar reports paths with forward slashes while root arrives with backslashes, so anything comparing them must go through path.relative. A plain string comparison makes the watch root look like a path outside itself, and the watcher then reports nothing without any error

npm 11.21 or newer is required, and engines says so. This is not about a script we need: npm below 11.21 does not block dependency install scripts, and it synthesises node-gyp rebuild for any package that ships a binding.gyp without an install script — better-sqlite3 is exactly that case. The rebuild needs MSVC, the Windows runner does not have it, and the node-gyp bundled with npm 10 cannot even recognise the Visual Studio 18 that is installed there:

gyp ERR! find VS unknown version "undefined" found at "C:\Program Files\Microsoft Visual Studio\18\Enterprise"

Nothing here needs a script: onnxruntime-node, better-sqlite3 and the six tree-sitter-* grammars all carry their binaries in the tarball, so with scripts blocked they load without npm install-scripts approve. This was found by CI, not by inspection — see Measured quality.

Development

npm run build       # compile TypeScript and prepare bin entries
npm run typecheck   # type check without emitting
npm test            # integration tests against a real stdio server
npm run probe       # environment verification

External quality benchmark. Mines questions from commit history in Flask, Gson and Fastify at pinned commits and compares against a grep baseline. Clones the three repositories (~46 MB) and needs several hours for the first index of each; later runs reuse the index and take minutes.

node scripts/bench-external.mjs --corpus flask     # also: gson, fastify

The scripts behind the analysis in docs/06-environment.md §18 live next to it: rank-sweep.mjs compares ranking strategies on built indexes, doc-regression.mjs checks that documentation queries keep working, language-diagnosis.mjs measures how answerable the questions are, and scale-control.mjs re-measures the same questions on a smaller index.

Documentation

These are the design notes behind the release — measurements, decisions and the open items. They are not shipped in the npm package, so the links point at the repository.

License

MIT