Report · marked 10 Oct 2026
swiftlang/swift
An agent is close to flying blind in this repository.
Swift · 70,485 stars · 33,171 files · branch main
31
/100
D
Instructions
3/27Whether the repo tells an agent how to behave before it starts guessing. Losing marks on agent instruction file and instruction quality.Setup
0/14Whether an agent can install the project and get it running without a human. Losing marks on deterministic install and discoverable commands.Verification loop
11/22Whether an agent can check its own work. This is the category that most decides whether agent output is trustworthy. Losing marks on test command is discoverable and continuous integration.Context economy
6/20Whether the repo fits in a context window, or fights it. Losing marks on no committed build output and file sizes fit in context.Navigability
9/10How quickly anything new can orient itself. Losing marks on repository description.
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
Test command is discoverable
Add a `test` script or a `test` target that runs the whole suite with no arguments. The convention is the interface — an agent tries `npm test` and `make test` before it tries reading your CI config.
The full marking
Every deduction below names the file or setting it came from.
Instructions 3/27 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
3/3
README has a clear getting-started section.
Setup 0/14 F
Whether an agent can install the project and get it running without a human.
✗Deterministic install
0/6
No lockfile. An agent installing dependencies may not get what CI got.
Commit the lockfile your package manager generates. Without it, an agent's install and your install are different builds, and 'works on my machine' becomes unfalsifiable.
✗Discoverable commands
0/6
No declared commands. An agent has to infer how to build and run this from the file tree.
Declare the handful of commands that matter in package.json scripts, a Makefile, or a justfile. Naming them turns guesswork into a lookup.
–Environment config
n/a
Not applicable — this reads as a library, with no environment to configure.
✗Pinned runtime version
0/2
No pinned runtime version.
Add a .nvmrc, .python-version, or equivalent so the agent's toolchain matches yours.
–Reproducible environment
n/a
Not applicable — a library doesn't need a container to be worked on.
Verification loop 11/22 C+
Whether an agent can check its own work. This is the category that most decides whether agent output is trustworthy.
✓Tests exist
8/8
18046 test files against 28372 source files.
e.g. benchmark/scripts/test_Benchmark_Driver.py, benchmark/scripts/test_compare_perf_tests.py, benchmark/scripts/test_utils.py
✗Test command is discoverable
0/7
There's no obvious way to run the tests. Even if tests exist, an agent won't reliably find the entry point.
Add a `test` script or a `test` target that runs the whole suite with no arguments. The convention is the interface — an agent tries `npm test` and `make test` before it tries reading your CI config.
✗Continuous integration
0/4
No CI config. Nothing outside a developer's laptop enforces correctness.
A CI workflow doubles as machine-readable documentation: it's the one file that states, unambiguously, the exact commands that must succeed.
✓Lint and format rules
3/3
.flake8 encodes the house style.
–Static type checking
n/a
Not applicable — the Swift compiler type checks every build.
Context economy 6/20 D
Whether the repo fits in a context window, or fights it.
✗No committed build output
3/6
Generated output is committed: coverage/.
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 50 patterns.
✗File sizes fit in context
0/6
162 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.
stdlib/public/stubs/Unicode/Common/ScalarPropsData.h — 2513KB
stdlib/public/stubs/Unicode/Apple/ScalarPropsData.h — 2511KB
lib/Sema/CSSimplify.cpp — 652KB
✗Repository weight
0/5
About 1397MB checked out. Large enough that cloning and searching are both slow.
Large binaries and vendored trees slow every operation an agent performs. Git LFS or a separate assets repo keeps the working tree navigable.
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 Swift Programming Language ## Setup ``` # TODO: the install command. No lockfile was found, so this could not be inferred. ``` ## Commands ``` # TODO: nothing declares a build or test command, so an agent has to guess. # This is the single most valuable section of this file. Fill it in. ``` ## Layout - `test/` 14995 source files - `validation-test/` 9165 source files - `lib/` 1315 source files - `include/` 871 source files - `stdlib/` 841 source files - `utils/` 389 source files ## Conventions - Tests live alongside the code they cover, following `benchmark/scripts/test_Benchmark_Driver.py`. - TODO: add the two or three conventions a newcomer always gets wrong here. ## Gotchas - `stdlib/public/stubs/Unicode/Common/ScalarPropsData.h` is 2513KB. It will not fit comfortably in context, so read it in parts. - No lockfile is committed, so an install here may not match what CI produced. --- 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/swiftlang/swift.md
A draft gets the commands right and stops at the things only a maintainer knows. what AGENTS.md is explains the format itself.
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