Report · marked 26 Aug 2026
evanw/esbuild
An agent can work here, but it will waste turns finding its footing.
Go · 40,019 stars · 350 files · branch main
58
/100
B-
Instructions
2/27Whether the repo tells an agent how to behave before it starts guessing. Losing marks on agent instruction file and instruction quality.Setup
14/14Whether an agent can install the project and get it running without a human. Full marks.Verification loop
19/22Whether an agent can check its own work. This is the category that most decides whether agent output is trustworthy. Losing marks on lint and format rules.Context economy
11/20Whether the repo fits in a context window, or fights it. Losing marks on no committed build output and file sizes fit in context.Navigability
8/10How quickly anything new can orient itself. Losing marks on written documentation.
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 2/27 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
2/3
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 14/14 A+
Whether an agent can install the project and get it running without a human.
✓Deterministic install
6/6
go.sum pins the dependency tree.
Found go.sum
✓Discoverable commands
6/6
Commands are declared where an agent will look for them.
Makefile
scripts/ directory
–Environment config
n/a
Not applicable — this reads as a library, with no environment to configure.
✓Pinned runtime version
2/2
The language runtime version is pinned.
go.mod declares a Go version
–Reproducible environment
n/a
Not applicable — a library doesn't need a container to be worked on.
Verification loop 19/22 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
37 test files against 199 source files.
e.g. cmd/esbuild/service_test.go, internal/bundler_tests/bundler_css_test.go, internal/bundler_tests/bundler_dce_test.go
✓Test command is discoverable
7/7
An agent can find and run `make test`.
✓Continuous integration
4/4
4 GitHub Actions workflows define what "passing" means.
✗Lint and format rules
0/3
No linter or formatter config. Style is tribal knowledge, so agent output will drift from yours.
A formatter config is the cheapest way to stop reviewing whitespace in agent diffs. It moves style from opinion to a command.
–Static type checking
n/a
Not applicable — the Go compiler type checks every build.
Context economy 11/20 B-
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 34 patterns.
✗File sizes fit in context
0/6
15 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.
internal/js_parser/js_parser.go — 644KB
internal/js_parser/js_parser_test.go — 481KB
scripts/end-to-end-tests.js — 344KB
✓Repository weight
5/5
About 20.9MB 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 An extremely fast bundler for the web ## Setup ``` go mod download ``` ## Commands ``` make esbuild make test # run the test suite, must pass before any commit make test-common make test-all make check-go-version make test-go ``` ## Layout - `internal/` 137 source files - `scripts/` 20 source files - `pkg/` 13 source files - `lib/` 10 source files - `cmd/` 7 source files - `compat-table/` 7 source files ## Conventions - Tests live alongside the code they cover, following `cmd/esbuild/service_test.go`. - CI defines what passing means. See `.github/workflows/ci.yml`, and keep it green. - TODO: add the two or three conventions a newcomer always gets wrong here. ## Gotchas - `internal/js_parser/js_parser.go` is 644KB. 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/evanw/esbuild.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.