# 1559 Agents Definitionsinstructions F57bb24c

> Standards for Copilot custom agent definition files

- Skill: `tools-only/1559-agents-definitionsinstructions-f57bb24c` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add tools-only/1559-agents-definitionsinstructions-f57bb24c`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tools-only/1559-agents-definitionsinstructions-f57bb24c/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- Author: tools-only (https://skillmd.com/u/tools-only)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/tools-only/1559-agents-definitionsinstructions-f57bb24c

---


# Agent Definition Standards

These instructions apply to custom agent definition files (for example: `.github/agents/*.agent.md`).

Goals:

- Keep agent behavior consistent and predictable across the repo
- Avoid drift between agents and the authoritative standards in `.github/instructions/`
- Prevent invalid YAML front matter and broken internal links

## Front Matter (Required)

Each `.agent.md` file MUST start with valid YAML front matter:

- Use `---` to open and close the front matter.
- Use spaces (no tabs).
- Keep keys simple and consistent.

Recommended minimum fields:

```yaml
---
name: { Human-friendly agent name }
description: { 1-2 sentences, specific scope }
tools:
  - { tool-id-or-pattern }
handoffs:
  - { other-agent-id }
---
```

### `name`

- Clear, human-friendly display name.
- Keep it stable (renames can confuse users and docs).

### `description`

- Describe what the agent does, and what it does NOT do.
- Mention any required standards (WAF, AVM-first, default regions) if applicable.

### `tools`

- List only tool identifiers that are actually available in the environment.
- Prefer patterns when supported (for example: `azure-pricing/*`, `azure-mcp/*`).
- If the agent should not call tools, set `tools: []` explicitly.
- Use `agent` (not `agent/runSubagent`) as the tool ID for subagent delegation.
- For long tool lists, prefer multi-line YAML arrays for readability:

```yaml
tools: [read/readFile, edit/createFile, agent, "azure-mcp/*"]
```

### `handoffs`

- Use `handoffs` to connect workflow steps (for example: Architect -> Bicep Plan -> Bicep Code).
- Only reference agents that actually exist in the repo.
- Use Title Case for the `agent` value matching the agent's display `name` (from frontmatter).
  For example: `agent: Architect` (matching `name: Architect` in frontmatter).
- Do not set `model` on individual handoff entries unless the target agent requires a specific
  model that differs from the agent's own frontmatter `model` value.

### `model`

> [!IMPORTANT]
> **Model selection is intentional and must not be changed without explicit approval.**

Agents that specify `Claude Opus 4.6` as priority model do so deliberately:

- **Opus-first agents** (requirements, architect, bicep-plan, bicep-code) require advanced
  reasoning for accurate planning decisions, WAF assessments, governance discovery, and
  high-quality code generation
- **GPT-5.3-Codex agents** (deploy, as-built, subagents) prioritize speed for execution,
  documentation generation, and isolated validation tasks

Current model assignments:

| Agent        | Model                    | Rationale            |
| ------------ | ------------------------ | -------------------- |
| Requirements | Opus 4.6                 | Deep understanding   |
| Architect    | Opus 4.6                 | WAF analysis + cost  |
| Bicep Plan   | Opus 4.6                 | Efficient planning   |
| Bicep Code   | Opus 4.6 / GPT-5.3-Codex | Code generation      |
| Deploy       | GPT-5.3-Codex            | Deployment execution |
| As-Built     | GPT-5.3-Codex            | Documentation gen    |
| Subagents    | GPT-5.3-Codex            | Fast validation      |

**Rules:**

1. **Never reorder models** to put a speed-optimized model before Opus if Opus is currently first
2. **Planning accuracy trumps cost/speed** — incorrect plans waste more resources than Opus costs
3. When adding `model` arrays, match the pattern of similar workflow-stage agents
4. Document any model changes in PR description with justification

## Agent Hierarchy

### Top-Level Agents

Top-level agents live in `.github/agents/` and are `user-invokable: true`. They correspond to
the 7-step workflow:

| Step | Agent              | File                          |
| ---- | ------------------ | ----------------------------- |
| 1    | Requirements       | `requirements.agent.md`       |
| 2    | Architect          | `architect.agent.md`          |
| 3    | Design (optional)  | `design.agent.md`             |
| 4    | Bicep Plan         | `bicep-plan.agent.md`         |
| 5    | Bicep Code         | `bicep-code.agent.md`         |
| 6    | Deploy             | `deploy.agent.md`             |
| 7    | As-Built           | `as-built.agent.md`           |
| —    | InfraOps Conductor | `infraops-conductor.agent.md` |
| —    | Diagnose           | `diagnose.agent.md`           |

### Subagents

Subagents live in `.github/agents/_subagents/` and are `user-invokable: false`. They isolate
expensive or specialized work from their parent agent's context window.

| Subagent                        | Parent Agent | Purpose                         |
| ------------------------------- | ------------ | ------------------------------- |
| `cost-estimate-subagent`        | Architect    | Pricing MCP queries             |
| `governance-discovery-subagent` | Bicep Plan   | Azure Policy REST API discovery |
| `bicep-lint-subagent`           | Bicep Code   | `bicep build` + `bicep lint`    |
| `bicep-review-subagent`         | Bicep Code   | AVM/security/naming code review |
| `bicep-whatif-subagent`         | Deploy       | `az deployment group what-if`   |

Subagent definition rules:

- Set `user-invokable: false` — subagents are never called directly by users.
- Set `agents: []` — subagents do not chain to other agents.
- Keep tool lists minimal — only the tools needed for their specific task.
- Use `GPT-5.3-Codex` as the default model for fast, isolated execution.
- Return structured results (PASS/FAIL, APPROVED/NEEDS_REVISION, etc.) so the parent
  agent can act on the verdict without parsing free-form text.

## Shared Defaults (Required)

All top-level workflow agents in `.github/agents/` MUST read the `azure-defaults` skill for shared
knowledge. Include a reference near the top of the agent body:

```text
Read `.github/skills/azure-defaults/SKILL.md` FIRST for regional standards, naming conventions,
security baseline, and workflow integration patterns common to all agents.
```

## Subagent Delegation Pattern

When an agent delegates work to a subagent, follow this pattern:

1. **Prepare inputs** — compile the data the subagent needs (resource list, file paths, etc.)
2. **Delegate** — call the subagent with a clear prompt containing the inputs
3. **Receive structured result** — the subagent returns a verdict/report
4. **Integrate** — use the subagent's output in the parent agent's artifact

This keeps the parent agent's context focused on its primary responsibility while the subagent
handles isolated, tool-heavy work (pricing queries, REST API calls, lint runs).

## Authoritative Standards (Avoid Drift)

When an agent outputs a specific document type, it MUST treat these as authoritative:

- Cost estimates: `.github/instructions/cost-estimate.instructions.md`
- Workload docs: `.github/instructions/workload-documentation.instructions.md`
- Markdown style: `.github/instructions/markdown.instructions.md`
- Bicep: `.github/instructions/bicep-code-best-practices.instructions.md`

If an agent contains an embedded template in its body, it MUST match the relevant instruction file.

## Templates in Agent Bodies

- Prefer short templates that are easy to keep aligned with standards.
- If you include fenced code blocks inside a fenced template, use quadruple fences (` ```` `)
  for the outer fence to avoid accidental termination.
- Keep example templates realistic, but do not hardcode secrets, subscription IDs, or tenant IDs.

## Links

- Prefer relative links for repo content.
- Verify links resolve from the agent file's directory (relative paths in Markdown are file-relative).
- Avoid linking to files that don't exist.

## Writing Style

- Use ATX headings (`##`, `###`).
- Keep markdown lines <= 120 characters.
- Use tables for decision matrices, comparisons, and checklists.

## Quick Self-Check (Before PR)

- `tools:` uses `agent` (not the deprecated `agent/runSubagent`) for subagent delegation
- `tools:` only contains valid tool IDs/patterns
- `handoffs:` only references real agents (including As-Built for Step 7)
- Handoff entries do not redundantly set `model` when the target agent already defines it
- The `azure-defaults` skill reference is correct
- Subagent files set `user-invokable: false` and `agents: []`
- Embedded templates match `.github/instructions/*` standards
- `npm run lint:md` passes