fmtlib/fmt

GitHub
https://github.com/fmtlib/fmt

A modern formatting library

  • c-plus-plus
  • chrono
  • cpp
  • cross-platform
  • floating-point
  • formatting
  • multiplatform
  • output
  • performance
  • printf
  • ranges
  • unicode
Stars:
25.9k
Language:
C++
Default branch:
main
Last scored:
Overall

At a glance

Rank
#297 of 401
#14 of 21 C++ repos
Checks passed
8 of 17
Full list below
Best set up for
Aider
Score 63.4
Needs most work for
Cursor
Biggest fix: Cursor rules (.cursor/rules) (+11.5 pts)

What it has

What it's missing

What to fix first

Pick an AI agent

Showing fixes for Claude Code

  1. 1
    AGENTS.md / CLAUDE.md
    Add an AGENTS.md covering project goals, layout, setup commands, and conventions. Aim for 800+ chars of real guidance (not boilerplate).
    +13.2 pts
  2. 2
    Reproducible dev env
    Add a Makefile or devcontainer or Dockerfile so the agent can set up the project in one command.
    +11.8 pts
  3. 3
    Type configuration
    Add a type config (tsconfig.json for JS/TS, mypy.ini or pyrightconfig.json for Python). Rust/Go/JVM/Scala/Swift/C#/OCaml/Haskell/Zig are typed by default.
    +7.9 pts

Score for each AI agent

Each agent weighs the checks by its own docs. Under each score are its top three. How each agent is scored →

Aider
#218 of 401
63.4
  • ✗.aider.conf.yml
  • ✓Linter / formatter config
  • ✓Test suite
Claude Code
#305 of 401
61.8
  • ✗AGENTS.md / CLAUDE.md
  • ✓Test suite
  • ✗Reproducible dev env
Codex
#309 of 401
60.8
  • ✗AGENTS.md / CLAUDE.md
  • ✓README
  • ✓Test suite
Devin
#295 of 401
60.7
  • ✗Reproducible dev env
  • ✓Dependency manifest
  • ✓Test suite
OpenHands
#269 of 401
60.0
  • ✓CI configuration
  • ✓Dependency manifest
  • ✗Reproducible dev env
Pi
#290 of 401
60.0
  • ✗AGENTS.md / CLAUDE.md
  • ✓Test suite
  • ✓Linter / formatter config
Kimi Code CLI
#310 of 401
58.7
  • ✗AGENTS.md / CLAUDE.md
  • ✓Test suite
  • ✓Dependency manifest
Gemini CLI
#307 of 401
55.4
  • ✗GEMINI.md
  • ✓README
  • ✓Test suite
Cursor
#312 of 401
54.0
  • ✗Cursor rules (.cursor/rules)
  • ✓README
  • ✗Type configuration

Does fmtlib/fmt have agent instructions?

An AGENTS.md (or CLAUDE.md) at the root tells AI coding agents how to build, test and work in the repo. A few agents also read a file of their own.

AGENTS.md / CLAUDE.md
None at the root (no AGENTS.md, CLAUDE.md, AGENT.md, .claude/CLAUDE.md or .claude/AGENTS.md)
Agent-specific files
None: no GEMINI.md, .cursor/rules, .openhands/setup.sh, .aider.conf.yml or .agents/skills
Repos that have one
10 of 21 C++ repos · 221 of 401 repos on the leaderboard · See examples →
Get a starter AGENTS.md

From the files the checks found. Fill in the commands, then commit it at the root.

# AGENTS.md

Guidance for AI coding agents working in fmtlib/fmt. A modern formatting library. Written mainly in C++.

## Where things are

- Dependencies are declared in `CMakeLists.txt`.
- Tests live in `test`.
- Lint and format rules are configured in `.clang-format`.
- CI is defined in `.github/workflows`; read it for the exact install, lint and test steps.
- Follow the conventions in `CONTRIBUTING.md`.

## Commands

<!-- Fill in the exact commands CI runs. -->
- Install: TODO
- Test: TODO
- Lint: TODO

All 17 checks · 8 passed

No .agents/skills/<name>/SKILL.md
No agent instructions file found
.aider.conf.yml· 0% pass
No .aider.conf.yml at repo root
CI configuration· 100% pass
9 GitHub Actions workflows
CONTRIBUTING guide· 100% pass
Guide present
No .cursor/rules/*.mdc or .cursorrules
Manifest present
No Makefile / devcontainer / Docker / equivalent found
GEMINI.md· 0% pass
No GEMINI.md at repo root
License file· 100% pass
License present
Config detected
No .openhands/setup.sh
No pre-commit / husky / lefthook found
README· 100% pass
README detailed (10,047 characters)
Manageable size· 100% pass
124 files
Test suite· 100% pass
Found /test
No type config found

How fmtlib/fmt compares

vs leaderboard average
7.4 pts below
Average 66.8
vs C++ average
0.1 pts above
Average 59.3
Stars among C++ repos
#12 of 21

Missing here, and how many repos have it

  • Type configuration · passed by 68% of leaderboard repos, 24% of C++ repos
  • Pre-commit / git hooks · passed by 29% of leaderboard repos, 29% of C++ repos
  • Reproducible dev env · passed by 22% of leaderboard repos, 10% of C++ repos

Passes checks most repos miss

  • Manageable size · only 16% of repos pass it

One fix for the most agents: AGENTS.md / CLAUDE.md would raise the score for all 9 agents, by up to 13.3 points.

Similar repos

Same language and host as this repo, closest in overall score.

All C++ repos →

Same topics, any language

Repos tagged with the same GitHub topics, most shared first.

Add a badge to your README

Paste this at the top of the README. It shows the score, and links back to this page.

Agent friendly score for github/fmtlib/fmt
[![Agent Friendly](https://agentfriendlycode.com/api/badge/github/fmtlib/fmt.svg)](https://agentfriendlycode.com/repo/github/fmtlib/fmt)

Check the score on every pull request

A GitHub Action posts one comment per pull request with how the score changed and why.