slug stringclasses 8
values | name stringclasses 8
values | filename stringclasses 8
values | artifact_kind stringclasses 8
values | vendor stringclasses 6
values | status stringclasses 3
values | spec_url stringclasses 1
value | docs_url stringclasses 7
values | first_released stringdate 2024-06-01 00:00:00 2025-08-01 00:00:00 | tools stringclasses 8
values | cross_tool bool 2
classes | supports_frontmatter bool 2
classes | supports_globs bool 2
classes | supports_imports bool 2
classes | supports_nested bool 2
classes | supports_multifile bool 2
classes | supports_user_scope bool 2
classes | activation stringclasses 8
values | size_limit stringclasses 1
value | summary stringclasses 8
values | strengths stringclasses 8
values | weaknesses stringclasses 8
values | verified_at stringdate 2026-08-01 00:00:00 2026-08-02 00:00:00 | sort_order int64 10 90 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
agents-md | AGENTS.md | AGENTS.md | agents_md | null | open-standard | https://agents.md | https://agents.md | 2025-08-01 | ["OpenAI Codex","Cursor","Amp","Aider","Zed","Google Jules","Gemini CLI","Factory","RooCode","opencode","Devin","Warp","goose","VS Code","GitHub Copilot coding agent","Windsurf","Junie (JetBrains)","Kilo Code","Augment Code","UiPath Autopilot","Semgrep","Phoenix","Ona"] | true | false | false | false | true | true | false | Always in scope; in a monorepo the nearest AGENTS.md to the edited file wins. | null | A plain-markdown README for coding agents, deliberately unopinionated: no frontmatter, no globs, no vendor keys. That minimalism is why it became the one file a dozen different agents will read, and why it carries the least per-file targeting power of any format here. | ["Read by more agents than any other format — one file covers most of a team's tooling","No schema to get wrong; a plain markdown file always parses","Nested files let a monorepo scope instructions per package"] | ["No glob targeting — every rule is loaded for every file, spending context","No imports, so shared rules must be duplicated across packages","No frontmatter means no machine-readable metadata for tooling to act on"] | 2026-08-02 | 10 |
claude-md | CLAUDE.md | CLAUDE.md | claude_md | Anthropic | vendor | null | https://code.claude.com/docs/en/memory | 2025-02-01 | ["Claude Code"] | false | false | false | true | true | true | true | Always in scope. Project file, plus nested files in subdirectories, plus a user-level file (~/.claude/CLAUDE.md) that applies across every project. | null | Claude Code's memory file. Shaped like AGENTS.md but with two things it lacks: @path imports, so shared rules live in one place, and a user-scope layer that follows the developer across repos rather than shipping with the code. | ["@path imports — shared conventions written once and pulled into each file","A user-scope file lets personal preferences live outside the team repo","Nested project files compose with the root file rather than replacing it"] | ["Single-vendor: no other agent reads it, so multi-tool teams maintain two files","No glob targeting, same context cost as AGENTS.md — path-scoped rules exist, but in a separate .claude/rules/ file, not in CLAUDE.md itself"] | 2026-08-02 | 20 |
cursor-rules | Cursor rules | .cursor/rules/*.mdc | cursor_rule | Cursor | vendor | null | https://cursor.com/docs/rules | 2025-02-01 | ["Cursor"] | false | true | true | true | true | true | false | Four modes set in frontmatter: Always Apply (every chat session), Apply Intelligently (the agent picks it by description), Apply to Specific Files (globs match the edited file), and Apply Manually (@-mentioned). Rules must carry the .mdc extension — a plain .md file in .cursor/rules is ignored. | null | The most expressive format here. Many small .mdc files, each with frontmatter declaring when it should load, so a rule about migrations only enters context when a migration is open. Costs the most to maintain and only one editor reads it. | ["Glob-scoped activation — the only widely-used format that keeps unrelated rules out of context","Description-based activation lets the agent pull a rule in on demand","Many small files are easier to review in a PR than one growing document"] | ["Cursor-only","Frontmatter is a schema, and a malformed .mdc silently stops applying","Fragmentation: rules spread over many files are easy to duplicate and contradict"] | 2026-08-02 | 30 |
copilot-instructions | Copilot instructions | .github/copilot-instructions.md | copilot_instructions | GitHub | vendor | null | https://docs.github.com/en/copilot/how-tos/provide-context | 2024-10-01 | ["GitHub Copilot","Copilot coding agent","VS Code"] | false | true | true | false | false | true | false | copilot-instructions.md is always in scope. Additional .github/instructions/*.instructions.md files load when their applyTo glob matches the open file. | null | Two layers: one always-on repo file, plus optional glob-scoped instruction files. Lives under .github/ rather than the repo root, which is the tell that it is aimed at the GitHub platform surface as much as the editor. | ["Reaches Copilot across the editor, github.com and the coding agent from one file","applyTo globs give per-path targeting without leaving the .github convention"] | ["Copilot-only","No imports; shared text is copied between instruction files","Buried under .github/, so contributors discover it less often than a root file"] | 2026-08-01 | 40 |
gemini-md | GEMINI.md | GEMINI.md | gemini_md | Google | vendor | null | https://github.com/google-gemini/gemini-cli | 2025-06-01 | ["Gemini CLI","Gemini Code Assist"] | false | false | false | true | true | true | true | Hierarchical memory: a global ~/.gemini/GEMINI.md, then the project file, then nested files, concatenated from broadest to narrowest. | null | Gemini CLI's memory file, structurally close to CLAUDE.md — @imports and a user-scope layer — which is why repos that carry both usually carry near-identical text in each. | ["@path imports and a global user file, same composition model as CLAUDE.md","Explicit hierarchy from global to local"] | ["Google-only","No glob targeting"] | 2026-08-01 | 50 |
windsurf-rules | Windsurf rules | .windsurf/rules/*.md | windsurf_rules | Windsurf | vendor | null | https://docs.devin.ai/desktop/cascade/memories | 2024-11-01 | ["Windsurf","Cascade"] | false | true | true | false | false | true | true | Four trigger modes in frontmatter: always_on, glob, model_decision, manual. The legacy single-file .windsurfrules is still read. | Per-rule and total character caps apply; long rules are truncated rather than rejected. | Cursor's activation model with a different vocabulary — trigger modes instead of rule types — plus hard character caps, which is the one place a format here will silently drop instructions rather than fail loudly. | ["Trigger modes give the same glob and on-demand targeting as Cursor rules","Workspace and global rule scopes"] | ["Windsurf-only","Character caps truncate silently — a long rule can be half-applied with no error","No imports"] | 2026-08-01 | 60 |
cline-rules | Cline rules | .clinerules | cline_rules | Cline | vendor | null | https://docs.cline.bot/customization/cline-rules | 2025-01-01 | ["Cline","Roo Code"] | false | false | false | false | false | true | true | Always in scope. Either a single .clinerules file or a .clinerules/ directory whose markdown files are all loaded. | null | A single file or a folder of files, all always-on. The folder form is the simplest way any format here lets you split rules into topics without also learning an activation model. | ["Directory form splits rules by topic with zero configuration","Toggleable rule sets for switching context between tasks"] | ["Cline-only","Everything is always-on — no targeting, so the folder form costs context"] | 2026-08-01 | 70 |
cursorrules | .cursorrules | .cursorrules | cursorrules | Cursor | deprecated | null | https://cursor.com/docs/rules | 2024-06-01 | ["Cursor (legacy)"] | false | false | false | false | false | false | false | Always in scope, single file at the repo root. | null | Cursor's original single-file format, superseded by .cursor/rules/*.mdc. Tracked here precisely because it is dead: how much of the ecosystem is still shipping a deprecated file is a measurable answer, and a large share of the "best cursor rules" pages on the web still teach this format. | ["One file, nothing to configure"] | ["Deprecated — do not start here","No targeting, no composition, no metadata"] | 2026-08-02 | 90 |
RuleStack: the agent config formats and what each one supports
One row per agent config format (AGENTS.md, CLAUDE.md and the rest): which tools read it, whether it supports frontmatter, globs, imports, nesting, multiple files and user scope, and the specification URL each of those was verified against.
| Rows in this cut | 8 |
| One row is | one config format |
| Cut | 2026-09-04 |
| Refreshed | Monthly, on the first of the month |
| Measured by | RuleStack |
| Method | https://toolproof.thecompound.tech/methodology |
| Licence | Creative Commons Attribution 4.0 International |
| Publisher | Compound Labs |
| Also on | Hugging Face · Zenodo |
How it is measured
Every support flag is read from the format's own published specification or documentation, with the URL stored beside it and a verification date. Nothing is inferred from what a format is generally understood to do.
What a citer needs to know
verified_atis the date the support matrix was last confirmed against the spec. A format whose spec has moved since then may have changed.
Files
| File | Format | Size |
|---|---|---|
rulestack-formats-2026-09-04.csv |
CSV | 0.01 MB |
rulestack-formats-2026-09-04.json |
JSON | 0.01 MB |
Every cut is also a GitHub release with the same files attached, so a citation can pin the exact edition it quoted.
Schema
| Column | Type | Empty in sample |
|---|---|---|
slug |
string | 0.0% |
name |
string | 0.0% |
filename |
string | 0.0% |
artifact_kind |
string | 0.0% |
vendor |
string | 12.5% |
status |
string | 0.0% |
spec_url |
string | 87.5% |
docs_url |
string | 0.0% |
first_released |
string | 0.0% |
tools |
array | 0.0% |
cross_tool |
boolean | 0.0% |
supports_frontmatter |
boolean | 0.0% |
supports_globs |
boolean | 0.0% |
supports_imports |
boolean | 0.0% |
supports_nested |
boolean | 0.0% |
supports_multifile |
boolean | 0.0% |
supports_user_scope |
boolean | 0.0% |
activation |
string | 0.0% |
size_limit |
string | 87.5% |
summary |
string | 0.0% |
strengths |
array | 0.0% |
weaknesses |
array | 0.0% |
verified_at |
string | 0.0% |
sort_order |
number | 0.0% |
Cite it
Compound Labs (2026). RuleStack: the agent config formats and what each one supports. RuleStack, https://rulestack.thecompound.tech. Cut of 2026-09-04. Creative Commons Attribution 4.0 International (CC BY 4.0). https://github.com/kyisaiah47/compound-datasets/tree/main/rulestack-formats
@dataset{compound_rulestack_formats_2026,
title = {RuleStack: the agent config formats and what each one supports},
author = {{Compound Labs}},
year = {2026},
publisher = {Compound Labs},
url = {https://github.com/kyisaiah47/compound-datasets/tree/main/rulestack-formats},
note = {Cut of 2026-09-04. Measured by RuleStack, https://rulestack.thecompound.tech},
license = {CC-BY-4.0}
}
The whole collection has a DOI, 10.5281/zenodo.22844096, at https://doi.org/10.5281/zenodo.22844096. It resolves to the newest Zenodo version. To pin the exact deposit this cut belongs to, cite 10.5281/zenodo.22844097 instead.
Attribution is the licence condition, and it is the only one. Quote a figure with the publisher, the product that measured it and the cut date, and there is nothing else to ask.
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