Report · marked 26 Aug 2026
parcel-bundler/parcel
An agent can work here, but it will waste turns finding its footing.
JavaScript · 44,019 stars · 5,447 files · branch v2
60
/100
B-
Instructions
1/27Whether the repo tells an agent how to behave before it starts guessing. Losing marks on agent instruction file and instruction quality.Setup
16/20Whether an agent can install the project and get it running without a human. Losing marks on environment config.Verification loop
22/22Whether an agent can check its own work. This is the category that most decides whether agent output is trustworthy. Full marks.Context economy
10/20Whether the repo fits in a context window, or fights it. Losing marks on no committed build output and file sizes fit in context.Navigability
10/10How quickly anything new can orient itself. Full marks.
Higher is better. Accent marks what is costing you most.
Fix these first
01
Agent instruction file
Add an AGENTS.md at the root: what the project is, how to install, how to run, how to test, and the two or three conventions a newcomer always gets wrong.
02
Instruction quality
Instructions earn their keep by naming exact commands. 'Run the tests with `pnpm test`' beats three paragraphs of philosophy.
03
File sizes fit in context
A single file that fills the context window forces an agent to work from fragments, and it will confidently edit code it never saw. Splitting the worst offenders pays for itself immediately.
The full marking
Every deduction below names the file or setting it came from.
Instructions 1/27 F
Whether the repo tells an agent how to behave before it starts guessing.
✗Agent instruction file
0/12
None found. Every agent that opens this repo starts from zero.
Add an AGENTS.md at the root: what the project is, how to install, how to run, how to test, and the two or three conventions a newcomer always gets wrong.
Looked for AGENTS.md, CLAUDE.md, .github/copilot-instructions.md, .cursorrules
✗Instruction quality
0/12
Nothing to judge, since there are no instructions.
Instructions earn their keep by naming exact commands. 'Run the tests with `pnpm test`' beats three paragraphs of philosophy.
✗README as an entry point
1/3
README exists but never explains how to get the thing running.
Give the README an Install and a Usage heading with real commands under each. Agents pattern-match on those headings.
Setup 16/20 A-
Whether an agent can install the project and get it running without a human.
✓Deterministic install
6/6
yarn.lock pins the dependency tree.
Found yarn.lock
✓Discoverable commands
6/6
Commands are declared where an agent will look for them.
package.json scripts (build, build-bundles, build-ts, build-native, build-native-release, build-native-canary…)
scripts/ directory
✗Environment config
0/4
Nothing documents the environment this needs. An agent will get a runtime error it can't diagnose.
Add a .env.example listing every variable with a safe placeholder value. It's the cheapest possible fix and it unblocks the whole first run.
✓Pinned runtime version
2/2
The language runtime version is pinned.
Found rust-toolchain
✓Reproducible environment
2/2
.devcontainer/devcontainer.json gives a known-good environment.
Verification loop 22/22 A+
Whether an agent can check its own work. This is the category that most decides whether agent output is trustworthy.
✓Tests exist
8/8
4360 test files against 3251 source files.
e.g. packages/configs/default/test/.babelrc, packages/configs/default/test/config.test.js, packages/core/codeframe/test/codeframe.test.js
✓Test command is discoverable
7/7
An agent can find and run `npm run check`.
✓Continuous integration
4/4
6 GitHub Actions workflows define what "passing" means.
✓Lint and format rules
3/3
.eslintrc.json encodes the house style.
–Static type checking
n/a
Not applicable — the Rust compiler type checks every build.
Context economy 10/20 C+
Whether the repo fits in a context window, or fights it.
✗No committed build output
3/6
Generated output is committed: node_modules/.
Add these to .gitignore and `git rm -r --cached` them. Generated files pollute search results, so an agent grepping for a function finds the compiled copy and edits the wrong file.
✓.gitignore hygiene
3/3
.gitignore covers 31 patterns.
✗File sizes fit in context
0/6
6 source files are over 100KB.
A single file that fills the context window forces an agent to work from fragments, and it will confidently edit code it never saw. Splitting the worst offenders pays for itself immediately.
.yarn/releases/yarn-4.9.1.cjs — 2940KB
flow-typed/npm/typescript_v3.3.x.js — 250KB
packages/core/integration-tests/test/cache.js — 204KB
✗Repository weight
4/5
About 65.7MB checked out, which is comfortable.
Here is your AGENTS.md
Drafted from what is actually in this repository: the install
command from your lockfile, the commands you already declare, your real directory layout. Anything
marked TODO needs a person. Save it at the root as AGENTS.md.
# AGENTS.md The zero configuration build tool for the web. 📦🚀 ## Setup ``` yarn install ``` ## Commands ``` yarn build # produce a build yarn test # run the test suite, must pass before any commit yarn lint # lint yarn format # format yarn check # lint and type check yarn build-bundles yarn build-ts yarn build-native ``` ## Layout - `packages/` 3183 source files - `crates/` 39 source files - `flow-typed/` 14 source files - `scripts/` 10 source files - `flow-libs/` 1 source file ## Conventions - Tests live alongside the code they cover, following `packages/configs/default/test/.babelrc`. - CI defines what passing means. See `.github/workflows/canary-release.yml`, and keep it green. - TODO: add the two or three conventions a newcomer always gets wrong here. ## Gotchas - `.yarn/releases/yarn-4.9.1.cjs` is 2940KB. It will not fit comfortably in context, so read it in parts. --- Drafted by agentreadme.com from what is in this repository. Everything marked TODO needs a human. Check it in as AGENTS.md at the root.
Open the raw markdown
or
curl -o AGENTS.md agentreadme.com/draft/parcel-bundler/parcel.md
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Think this mark is wrong?
Every deduction above names the file it came from, so this can be settled by looking. If a check missed something, that is a rule worth fixing.