build-explain

build-explain is a command for Claude Code from sigistry/marketplace. It costs 14 tokens per session (849 once invoked), scanned A, original, MIT.

A command for explaining how a repository builds and tests its packages, including projects that contain multiple packages or services in one monorepo.

In plain words
What is it for?
Use it to discover build tools, map available targets, and find the fastest command for building or testing one package or module.
Why use it?
Build tools and dependency graphs can be difficult to understand, and running the wrong command can waste time. This identifies the relevant build system and target.

Command for Claude Code

Written for Claude Code: argument-hint in frontmatter. Also seen: model in frontmatter.

Part of the codebase-navigator plugin — 2 skills, 4 commands, 3 agents shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/sigistry/marketplace/build-explain
Clone the repo
git clone --depth 1 https://github.com/sigistry/marketplace

Made for: Claude Code.

Or install codebase-navigator, the plugin that ships this one along with the rest of its 2 skills, 4 commands, 3 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for build-explain

README.md
[![agentmods](https://agentmods.dev/badge/commands/sigistry/marketplace/build-explain.svg)](https://agentmods.dev/commands/sigistry/marketplace/build-explain)
Your own site
<a href="https://agentmods.dev/commands/sigistry/marketplace/build-explain"><img src="https://agentmods.dev/badge/commands/sigistry/marketplace/build-explain.svg" alt="Measured on agentmods" height="20"></a>
Per session 14 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 849 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00014 $0.00849
Opus 5 $0.00007 $0.00425
Sonnet 5 $0.00003 $0.00170
Haiku 4.5 $0.00001 $0.00085

Measured 6d ago against content hash b61e508a5374, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

build-explain scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

plugins/codebase-navigator/commands/build-explain.md · 53 lines

How it starts

The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Decode this repository's build system so you can build and test without holding the whole dependency graph in your head. Use this when make, Bazel, Gradle, or a monorepo task runner is opaque and you just need the right command for one package. $ARGUMENTS may name a target, package, or module to focus on (e.g. //services/api:test, web, :app:assembleDebug); with no argument, map the whole build.

Process

Step 1: Detect the build system

Identify the driver(s) from their manifests, a repo can have more than one layer (a top-level task runner over a per-language build). Consult the build-system-decode skill (build-systems.md) for per-tool details.

Manifest Build system
Makefile Make
BUILD, BUILD.bazel, WORKSPACE, MODULE.bazel Bazel
build.gradle(.kts), settings.gradle Gradle
pom.xml Maven
package.json scripts, lockfile npm / pnpm / yarn scripts
nx.json, project.json Nx
turbo.json Turborepo
CMakeLists.txt CMake
Cargo.toml ([workspace]) cargo
go.mod, go.work go build

Step 2: Enumerate the targets

List what you can actually run and what each does, do not invent targets. Use the tool's own introspection rather than parsing by eye:

  • Make: read .PHONY and rule names; make -qp / make help if present.
  • Bazel: bazel query //..., bazel query 'deps(//target)'.
  • Gradle: ./gradlew tasks --all, :project:dependencies.
  • Maven: mvn -q help:describe, the <modules> list.
  • npm/pnpm/yarn: the scripts block; workspace list.
  • Nx/Turbo: nx graph / turbo run build --dry, project.json/turbo.json pipeline/tasks.
  • cargo/go: cargo metadata, go list ./....

Step 3: Map the dependency graph

Show which packages/modules depend on which, and where the slow edges are. Identify the difference between building the world and building one package plus only its dependencies. For monorepos, apply the build-system-decode skill's monorepo-patterns.md (workspaces, project graph, affected/changed detection).

Read the full file on GitHub · 53 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 53 lines · 14 tokens per session scan A b61e508a5374

Subscribe to this mod's changes

build-explain is a command published in the GitHub repository sigistry/marketplace (3 stars, last pushed 2d ago), licensed MIT. It adds 14 tokens to every session and 849 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.