design-agent

name	design-agent
description	Design and implement a new ADK sub-agent with tools, state contracts, and eval cases
argument-hint	<agent-name> <description>
allowed-tools	Read, Write, Edit, Bash, Glob, Grep

Design New Sub-Agent

Create sub-agent: $ARGUMENTS

Step 1 — Define Responsibilities

• What tasks does this agent handle?
• What it does NOT handle (boundary with existing agents)?
• Input/output contract

Step 2 — Design State Contract

• State keys this agent reads (from parent session)
• State keys this agent writes (to parent session)
• Add all new keys to mortgage_concierge/shared_libraries/constants.py

Step 3 — Design Internal Tools

• List methods the agent uses internally
• Each wraps as FunctionTool(self._method)

Step 4 — Write Agent Prompt

Follow pattern from LoanSimulationAgent or PackageEvaluatorAgent:

• TOOL INSTRUCTIONS section
• OUTPUT FORMAT section
• Domain-specific guidelines

Step 5 — Create Pydantic Models

• Input models (specifications, criteria)
• Output models (results, assessments)
• Place in mortgage_concierge/sub_agents/<name>/models.py

Step 6 — Create Eval Cases

• Add evalset JSON in tests/eval/data/
• Queries that trigger the agent's wrapper tool

Step 7 — Implement

• mortgage_concierge/sub_agents/<name>/__init__.py
• mortgage_concierge/sub_agents/<name>/agent.py
• mortgage_concierge/sub_agents/<name>/models.py
• mortgage_concierge/tools/<name>_tools.py (wrapper)
• Register in agent.py and prompt.py

Step 8 — Write Tests

• Unit tests for agent methods and wrapper tool
• Integration tests for full flow

Reference

• Canonical pattern: mortgage_concierge/sub_agents/loan_simulation/agent.py
• Wrapper pattern: mortgage_concierge/tools/simulation_tools.py