# Mode Builder

> Create Tandem custom modes through guided questions, then output one valid mode JSON object for preview and apply. Use when this capability is needed.

- Skill: `tomevault-io/mode-builder` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/mode-builder`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/mode-builder/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/mode-builder

---


# Mode Builder

## Purpose

Help users create a safe, useful Tandem custom mode even if they are not technical.

## Core Rules

1. Ask follow-up questions with `ask_followup_question` whenever key details are missing.
2. Keep questions plain-language and low-jargon.
3. Default to safe behavior when uncertain.
4. Final answer must include exactly one JSON object in a fenced `json` block.
5. The JSON object must use only these fields:
   - `id`
   - `label`
   - `base_mode`
   - `icon`
   - `system_prompt_append`
   - `allowed_tools`
   - `edit_globs`
   - `auto_approve`
6. Do not include comments in JSON.
7. Do not include extra top-level keys like `scope`, `source`, or metadata.

## Valid `base_mode` values

- `immediate`
- `plan`
- `orchestrate`
- `coder`
- `ask`
- `explore`

## Practical Guidance

1. Recommend `ask` or `explore` for beginners.
2. Recommend `coder` only when the user explicitly wants code edits.
3. Use conservative `allowed_tools` first, then expand only if requested.
4. Use `edit_globs` whenever edits should be constrained.
5. Keep `auto_approve` set to `false` unless the user explicitly asks otherwise.

## Output Contract

When ready, output:

```json
{
  "id": "example-mode",
  "label": "Example Mode",
  "base_mode": "ask",
  "system_prompt_append": "Clear mode instructions.",
  "allowed_tools": ["read", "search", "glob"],
  "edit_globs": ["docs/**", "*.md"],
  "auto_approve": false
}
```

No additional text after the final JSON block.

---
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<!-- tomevault:4.0:skill_md:2026-04-11 -->