Skills/PyPI/mcp-nixos

mcp-nixos@3.1.0

VERIFIED· not started

Publisher claims: "Model Context Protocol server for NixOS, Home Manager, and nix-darwin resources" Observed in sandbox: no network, touches nothing outside the project, writes no memory.

Registry PyPI (MCP server)Publisher james-brink-brink.james · publishing for 595 daysInstalls 3,771Last detonated 6d ago
$claude mcp add mcp-nixos -- uvx mcp-nixos
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Coverage

Not started: dependency install failed; the server itself was not observed.
Tested
the dependency install step · every file read, file written and host contacted by what ran
Not tested
server startup · the tool list · tool behavior

What this means for the label: Verified here covers what ran. The server's tools were not exercised with a real credential, so nothing about their behavior is asserted; the credential summary below says what to do with that.

Before you give it your token

It will ask for
no credential variables read in the code
Where it talks to
nixos.org (its own)Also nix.dev, flakehub.com, notashelf.dev, noogle.dev, devbox.sh — not the publisher's domain; check what for before connecting.
What the honeypot saw
no credential files read · no network
What we could not test
server startup · the tool list · tool behavior

Connect it under the guard. Not started: dependency install failed; the server itself was not observed. The code names no credential variable and talks to nixos.org, its own; the guard pins the network to what the honeypot saw and logs every call.

$vet-skills run --net declared -- uvx mcp-nixos

Never paste a credential into a chat, a ticket or a report, including ours. How the guard holds it.

Is [email protected] safe to install?

KillerSkills ran it in the KillerSkills honeypot sandbox (2 scenarios; not started: dependency install failed; the server itself was not observed) on 2026-11-08 and scored it 83/100 (Verified). In what ran, nothing we could detect went wrong: no undeclared network egress, no credential reads, no persistent instruction writes. What it does with a real credential was not observed; the static findings and the publisher carry the rest of the score. Summary: no network, touches nothing outside the project, writes no memory.

Behavior trace

Honeypot run · 0 s · 2 scenarios · 0 deviations
t+CategoryObserved action
0.0sprocessno install scripts in bundle
0.1sprocessdependency install exit 1 ·
0.1sclaimednot started: dependency install failed (exit 1); the server itself was not observed
0.1sprocessscript backend runs setup only
0.1sprocessno install scripts to re-run

Static findings

MEDIUM
Python subprocess execution detectedtests/test_env_file_safety.py:49 · Python subprocess execution detectedreturn subprocess.run(Fix: Build commands from fixed arguments, never from interpolated strings; prefer an API client over shelling out.
AST05
MEDIUM
Access to sensitive file pathstests/test_env_file_safety.py:3 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filescontains a non-UTF-8 `.env`.Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_env_file_safety.py:61 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files(tmp_path / ".env").write_bytes(b"\x9d\x9e\xff\x00binary garbage\xc3\x28")Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathsmcp_nixos/__init__.py:14 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files# pydantic-settings `Settings()`, which eagerly reads `.env` from the caller'sFix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Python subprocess execution detectedtests/test_env_file_safety.py:99 · Python subprocess execution detectedresult = subprocess.run(Fix: Build commands from fixed arguments, never from interpolated strings; prefer an API client over shelling out.
AST05
MEDIUM
Access to sensitive file pathstests/test_env_file_safety.py:60 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files"""Non-UTF-8 bytes in ./.env must not crash import of mcp_nixos.server."""Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathsmcp_nixos/__init__.py:19 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files# `.env`, so neutralising the lookup is safe. Respect an explicit override.Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Process kill commandtests/test_flake_inputs.py:214 · Process kill command — agent can terminate processesmock_process.kill = MagicMock() # kill() is sync, not asyncFix: Build commands from fixed arguments; do not interpolate untrusted strings into a shell.
AST05
MEDIUM
Python subprocess execution detectedtests/test_env_file_safety.py:78 · Python subprocess execution detectedresult = subprocess.run(Fix: Build commands from fixed arguments, never from interpolated strings; prefer an API client over shelling out.
AST05
MEDIUM
Access to sensitive file pathstests/test_env_file_safety.py:6 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system fileswhich runs python-dotenv on `.env` in the process CWD. A binary / git-cryptFix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathsmcp_nixos/__init__.py:15 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files# CWD via python-dotenv. A non-UTF-8 `.env` (git-crypt ciphertext, sops-Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_store.py:117 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesresult = await _store_ls("/etc/passwd", 500)Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_store.py:124 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesresult = await _store_ls("/nix/store/../etc/passwd", 500)Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_flake_inputs.py:154 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesassert _validate_store_path("/nix/store/../etc/passwd") is FalseFix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_flake_inputs.py:150 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesassert _validate_store_path("/etc/passwd") is FalseFix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_env_file_safety.py:66 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files"mcp_nixos.server failed to import with a non-UTF-8 .env in CWD. "Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_store.py:211 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesresult = await _store_read("/nix/store/../etc/passwd", 20)Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Process kill commandtests/test_flake_inputs.py:491 · Process kill command — agent can terminate processesmock_process.kill = MagicMock() # kill() is sync, not asyncFix: Build commands from fixed arguments; do not interpolate untrusted strings into a shell.
AST05
MEDIUM
Access to sensitive file pathstests/test_tools.py:1468 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesresult = await nix_fn(action="info", query="../../etc/passwd", source="nix-dev")Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
MEDIUM
Access to sensitive file pathstests/test_tools.py:1479 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesquery="%2e%2e/%2e%2e/etc/passwd",Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05

Cost to the agent

Instructions loaded
≈6,909 tok
4 files · 77 in bundle
Tool list per prompt
≈0 tok
0 tools · 0 per tool
Handshake
no reply
launch to tools/list, stdio
Undocumented tools
0
description under 20 chars · avg 0

Tokens estimated at four characters each. The tool list is re-read by the agent on every turn, so it is the number to compare between servers that do the same job: ranked across the index.

Known vulnerabilities

No advisories in OSV for mcp-nixos@3.1.0 as of 6d ago. This is the package itself, not its dependencies.