Which coding agents read .cursor/rules/*.mdc?
Cursor project rules with frontmatter (description, globs, alwaysApply).
A cell reads "unverified" when the page we checked does not mention the file. We then have no source, which says nothing about whether the tool reads it. A cell reads "migration only" when the page mentions the file only as input to a migration command such as /init.
- Reads 1
- Migration only 1
- Unverified 2
| Tool | Status | Note | Official source | Checked |
|---|---|---|---|---|
| Cursor | Reads |
Project rules live in .cursor/rules as .mdc files. A plain .md file in that folder is ignored. |
||
| Claude Code | Migration only |
Mentioned only in the /init migration section, as Cursor rules in .cursor/rules/. /init incorporates the relevant parts into the generated CLAUDE.md. The page does not say Claude Code loads these files itself. |
||
| Codex | Unverified |
Not mentioned on the cited page, or in the configuration reference entry for project_doc_fallback_filenames, when checked. |
||
| GitHub CopilotRepository custom instructions on GitHub.com (cloud agent, code review) | Unverified |
Not mentioned on the cited page or in GitHub's "Support for different types of custom instructions" table when checked. That table names copilot-instructions.md, *.instructions.md, AGENTS.md, CLAUDE.md, GEMINI.md and, for code review, REVIEW.md. |
Data
These rows come from the instruction file matrix, also published as matrix.json. Cells marked unverified are listed on one page.
Other instruction files
AGENTS.mdAGENTS.override.mdCLAUDE.mdGEMINI.md.cursorrules.claude/rules/ *.md .github/copilot-instructions.md .github/instructions/ *.instructions.md
How to cite
The data and the text are under CC BY 4.0. Credit the project, link the license, and say what you changed. A cell is a dated reading of an official page, so give the date of the cell, which is shown on it, or the date the matrix was last reviewed.
Suggested credit: "Rulefiles data by Rulefiles contributors, https://rulefiles-preview.pages.dev/matrix/, last reviewed 2026-10-16, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)."
Quoted excerpts of the sources belong to their authors. Link the official page of the cell when you rely on it.