Agent Development

Overview

Design and build AI agents that effectively use tools, manage memory, plan multi-step tasks, coordinate with other agents, and operate within safety guardrails. This skill covers the full agent development lifecycle from architecture through evaluation, with emphasis on observable, testable, and safe agent behavior.

Phase 1: Agent Design

Define the agent's purpose and scope
Identify required tools and capabilities
Design memory architecture (short-term, long-term)
Plan agent loop structure (observe, think, act)
Define safety boundaries and guardrails

STOP — Present agent design to user for approval before implementation.

Agent Architecture Decision Table

Agent Type	When to Use	Loop Pattern	Complexity
Single-turn tool user	Simple queries with tool calls	Request -> Tool -> Response	Low
ReAct agent	Multi-step reasoning tasks	Thought -> Action -> Observation -> loop	Medium
Plan-and-execute	Complex tasks with dependencies	Plan -> Execute steps -> Validate	Medium-High
Multi-agent orchestrator	Parallel/specialized sub-tasks	Dispatch -> Collect -> Synthesize	High
Autonomous loop (Ralph-style)	Long-running iterative development	Plan -> Build -> Verify -> Exit gate	High

Phase 2: Implementation

Build the agent loop with tool dispatch
Implement memory management (context window, persistence)
Add planning and decomposition logic
Integrate error recovery and retry patterns
Implement output validation

STOP — Run smoke tests on the agent loop before adding complexity.

Tool Use Patterns

Tool Definition Best Practices

Principle	Rule	Example
Clear naming	verb-noun format	`search_documents` , `create_file`
Detailed descriptions	Include when to use AND when NOT to use	"Use for keyword search. Do NOT use for semantic similarity."
Well-typed parameters	Descriptions and examples on every param	`query: string // "e.g., 'user authentication'"`
Predictable returns	Consistent format across tools	Always return `{ success, data, error }`
Self-correcting errors	Help agent recover	"Invalid date format. Expected ISO 8601: YYYY-MM-DD"

Tool Selection Strategy

Given a task:
1. Identify required information and actions
2. Map to available tools
3. Determine tool call order (dependencies)
4. Execute with result validation
5. Retry or try alternative tool on failure

Tool Design Principles

Composable: small tools that combine for complex tasks
Idempotent: safe to retry without side effects (where possible)
Observable: return enough context for the agent to verify success
Bounded: timeouts and size limits on all operations
Documented: every parameter and return value described

Memory Management

Memory Type Decision Table

Type	Duration	Storage	Use Case
Working Memory	Current turn	Context window	Active reasoning
Short-term Memory	Current session	In-context or buffer	Recent conversation
Long-term Memory	Across sessions	Database/file	Learned patterns, user prefs
Episodic Memory	Specific events	Indexed store	Past task outcomes
Semantic Memory	Knowledge	Vector DB	Domain knowledge retrieval

Context Window Management

Strategy: Sliding window with importance-based retention

1. Always retain: system prompt, tool definitions, current task
2. Summarize: older conversation turns into compressed summaries
3. Evict: least relevant context when approaching limit
4. Retrieve: pull relevant long-term memory on demand

Budget allocation:
  System prompt + tools: ~20%
  Current task context:  ~40%
  Conversation history:  ~25%
  Retrieved memory:      ~15%

Memory Update Triggers

Trigger	Action
User correction	Update learned patterns
Task completion	Store outcome and approach
Error recovery	Record what failed and what worked
New domain knowledge	Index for future retrieval

Planning Strategies

Hierarchical Task Decomposition

1. Break high-level goal into sub-goals
2. For each sub-goal, identify required actions
3. Order actions by dependencies
4. Execute with checkpoints between phases
5. Re-plan if intermediate results change the approach

ReAct Pattern (Reason + Act)

Thought: I need to find the user's recent orders to answer their question.
Action: search_orders(user_id="123", limit=5)
Observation: Found 5 orders, most recent is #456 from yesterday.
Thought: The user asked about order #456. I have the details now.
Action: respond with order details

Plan-and-Execute Pattern

1. Create a complete plan before any action
2. Execute each step, checking preconditions
3. After each step, validate the result
4. If a step fails, re-plan from current state
5. Never modify the plan mid-step (finish or abort first)

Reflection Pattern

After completing a task:
1. Was the result correct?
2. Was the approach efficient?
3. What could be improved?
4. Should any memory be updated?

Phase 3: Evaluation and Safety

Build evaluation harness with test scenarios
Measure accuracy, efficiency, and safety metrics
Test edge cases and adversarial inputs
Add monitoring and logging
Implement circuit breakers for runaway behavior

STOP — All safety guardrails must be tested before deployment.

Multi-Agent Coordination

Coordination Pattern Decision Table

Pattern	Description	Use When
Orchestrator	Central agent delegates to specialists	Clear task hierarchy
Pipeline	Agents process in sequence	Linear workflows
Debate	Agents propose and critique	Need diverse perspectives
Voting	Multiple agents, majority wins	Uncertainty in approach
Supervisor	One agent monitors others	Safety-critical tasks

Communication Protocol

Agent-to-Agent message:
{
  "from": "planner",
  "to": "executor",
  "type": "task_assignment",
  "content": { "task": "...", "context": "...", "constraints": "..." },
  "priority": "high",
  "deadline": "2025-01-15T10:00:00Z"
}

Coordination Rules

Define clear ownership boundaries
Use structured messages between agents
Implement deadlock detection
Set timeouts for inter-agent communication
Log all inter-agent messages for debugging

Evaluation Framework

Metrics Decision Table

Metric	What It Measures	How to Measure	Target
Task Success Rate	Correct completions / total	Automated + human eval	> 90%
Efficiency	Steps vs optimal path	Step count comparison	< 2x optimal
Tool Accuracy	Correct tool calls / total	Log analysis	> 95%
Safety	Violations / total interactions	Guardrail checks	0 violations
Latency	Time to complete task	Wall clock	< SLA
Cost	Token usage per task	API usage tracking	Within budget

Evaluation Dataset Structure

json

{
  "test_cases": [
    {
      "id": "tc_001",
      "input": "Find all orders over $100 from last week",
      "expected_tools": ["search_orders"],
      "expected_output_contains": ["order_id", "amount"],
      "category": "retrieval",
      "difficulty": "easy"
    }
  ]
}

Safety Guardrails

Input Guardrails

Detect and reject prompt injection attempts
Validate all user inputs before processing
Rate limit requests per user/session
Content filtering for harmful requests

Output Guardrails

Validate tool call arguments before execution
Check outputs for sensitive information (PII, secrets)
Enforce response format constraints
Prevent infinite tool call loops

Operational Guardrails

Maximum tool calls per task (circuit breaker)
Maximum tokens per response
Timeout for total task duration
Escalation to human when confidence is low
Audit logging for all actions

Circuit Breaker Thresholds

Condition	Threshold	Action
Max tool calls per task	20	Stop execution, return error
Max consecutive errors	3	Stop, log, return graceful error
Max task duration	5 minutes	Timeout, return partial result
Max tokens generated	10,000	Stop generation
Pattern repeats	5 identical errors	Open circuit, alert operator

Prompt Engineering for Agents

System Prompt Structure

1. Identity and purpose (who the agent is)
2. Available tools (what it can do)
3. Constraints (what it must not do)
4. Output format (how to respond)
5. Examples (few-shot demonstrations)
6. Error handling (what to do when stuck)

Key Prompt Patterns

Scratchpad: encourage step-by-step reasoning before action
Self-correction: "If your first approach fails, try..."
Confidence calibration: "Only proceed if you are confident"
Graceful degradation: "If you cannot complete the task, explain why"

Anti-Patterns / Common Mistakes

Anti-Pattern	Why It Is Wrong	What to Do Instead
Calling tools without reasoning	Wastes calls, misses context	Use ReAct pattern (think first)
No max iteration limit	Infinite loops, runaway costs	Set circuit breaker thresholds
Trusting all tool outputs	Corrupted data propagates	Validate tool results
Hardcoded tool sequences	No adaptability to failures	Dynamic tool selection based on state
No error recovery strategy	Agent gets stuck on first failure	Implement retry with alternatives
Apologizing instead of acting	Wastes user time	Take corrective action, then report
Over-reliance on single tool	Fragile if that tool fails	Provide fallback tools
No evaluation framework	Shipping blind, no quality signal	Build eval harness before deployment
Unlimited context growth	Context overflow, degraded quality	Implement memory management

Integration Points

Skill	Integration
`mcp-builder`	MCP servers provide tools for agents
`planning`	Agent planning uses structured plan generation
`autonomous-loop`	Ralph-style loops are a specialized agent pattern
`dispatching-parallel-agents`	Multi-agent coordination pattern
`circuit-breaker`	Operational safety for agent loops
`verification-before-completion`	Agent output validation
`test-driven-development`	TDD for agent tool implementations

Skill Type

FLEXIBLE — Adapt the agent architecture, memory strategy, and coordination patterns to the specific use case. Safety guardrails and evaluation frameworks are strongly recommended for all production agents.

agent-development

NPX Install

Tags

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