Prbody MCP Server

prbody

Every repo has a PR template, and every PR author fills it in differently — or pastes over it, or leaves the headings empty. prbody takes the mechanical part out of the author's hands: you hand it the template, the PR's commits, and the issue it closes, and it hands back the body with the template's placeholders filled in, the same way every time.

Four placeholders are pinned, spelled exactly like this:

• {{title}} — the PR title, or the empty string when no title is supplied.
• {{summary}} — one line per commit, in the order the commits were given: - <subject>.
• {{commits}} — one line per commit, in the same order, with the short hash appended: - <subject> (<hash7>), where <hash7> is the first 7 characters of the commit's hash (the whole hash when it is shorter than 7).
• {{issue_link}} — Closes #<issue_number> when an issue number is supplied, or the empty string when it is not.

Every occurrence of each known placeholder is replaced. Any other {{...}} span — anything from {{ to the next }} — is left in the body exactly as written, and its inner name, trimmed of surrounding whitespace, is reported in unfilled_placeholders (distinct, sorted ascending), so a template asking for something prbody does not know about is visible instead of silently dropped. A {{ with no later }} is not a placeholder at all: it is left untouched and unreported. Replacement text is never rescanned, so a {{...}} sequence that arrives inside a title or a commit subject stays literal.

The result also reports commit_count (the number of commits) and closes_issue (true exactly when an issue number was supplied). Malformed input — a missing, empty, or non-string template; commits missing, not an array, or empty; a commit entry that is not an object or whose hash or subject is missing, empty, or non-string; an issue_number that is not an integer of at least 1; or a title that is empty or non-string when present — is a validation error naming the offending path (for example commits[1].subject must be a non-empty string), with no partial result. Unknown extra fields are ignored, including extra fields inside commit entries. The computation is pure and local: no network, no configuration, and no repository is read or touched — prbody only fills the template it is given.

CLI

npx @reneturcios/prbody build --input args.json
npx @reneturcios/prbody --version

args.json contains the full arguments object:

{
  "template": "## {{title}}\n\n### Commits\n{{commits}}\n\n{{issue_link}}",
  "commits": [
    { "hash": "abc1234def5678", "subject": "Add login form" },
    { "hash": "9876fedcba4321", "subject": "Fix redirect loop" }
  ],
  "issue_number": 42,
  "title": "Login rework"
}

The result is printed as JSON:

{
  "body": "## Login rework\n\n### Commits\n- Add login form (abc1234)\n- Fix redirect loop (9876fed)\n\nCloses #42",
  "unfilled_placeholders": [],
  "commit_count": 2,
  "closes_issue": true
}

Exit codes: 0 on success, 1 on a runtime error (including an unreadable or invalid input file, or invalid input), 2 on a usage error.

MCP server

npx -y @reneturcios/prbody mcp

MCP client config:

{
  "mcpServers": {
    "prbody": {
      "command": "npx",
      "args": ["-y", "@reneturcios/prbody", "mcp"]
    }
  }
}

Tools

• build_pr_body — Build a pull request body by filling the repo's PR template with the PR title, a summary of its commits, the full commit list, and the closing line for its linked issue.

  • template (string, required, non-empty) — the repo's PR template text, with {{...}} placeholders
  • commits (array, required, non-empty) — commits of the PR, oldest first; each entry is an object with hash (string, required, non-empty) and subject (string, required, non-empty)
  • issue_number (integer, optional, at least 1) — the linked issue number
  • title (string, optional, non-empty when present) — the pull request title

  Returns {body, unfilled_placeholders, commit_count, closes_issue}.

Docker

docker run -i ghcr.io/cloudcorprecords/prbody
docker run --rm -v "$PWD:/w" ghcr.io/cloudcorprecords/prbody build --input /w/args.json

Development

npm install
npm run build   # tsc -> dist/
npm test        # tsx --test test/*.test.ts (pure local, no network)
npm run dev     # run the CLI from source

License

MIT — Copyright (c) 2026 Rene Turcios