| description | Standards for Copilot custom agent definition files |
| applyTo | **/*.agent.md |
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:
---
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/*).
- If the agent should not call tools, set
tools: [] explicitly.
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).
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) require advanced reasoning
for accurate planning decisions, WAF assessments, and governance discovery
- Sonnet-first agents (bicep-code, deploy) prioritize speed for implementation tasks
Rules:
- Never reorder models to put Sonnet before Opus if Opus is currently first
- Planning accuracy trumps cost/speed - incorrect plans waste more resources than Opus costs
- When adding
model arrays, match the pattern of similar workflow-stage agents
- Document any model changes in PR description with justification
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:
Read `.github/skills/azure-defaults/SKILL.md` FIRST for regional standards, naming conventions,
security baseline, and workflow integration patterns common to all agents.
All agent definitions live in .github/agents/. Subagents live in
.github/agents/_subagents/.
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: only contains valid tool IDs/patterns
handoffs: only references real agents
- The
azure-defaults skill reference is correct
- Embedded templates match
.github/instructions/* standards
npm run lint:md passes