Architecting Agents Protocol
Architecting Agents Protocol
Provides design patterns for agent context management.
Cost Warning (CRITICAL)
Before using sub-agents, understand the costs:
| Approach | When to Use | |:---------|:------------| | Inline | Most tasks | | Fork | Isolation needed | | Subagent | Parallelization only (High Cost) |
Default Recommendation: Use context: fork in skills for isolation. Subagents are ONLY appropriate when parallelization benefit clearly exceeds 20K token startup cost AND quota overhead.
See references/subagent-risks.md for detailed evidence.
Pattern Index
| Pattern | Purpose | When to Use | |:--------|:--------|:------------| | Computer Access | Persistent context via filesystem | Agent needs state persistence | | Multi-Layer Actions | Hierarchical tool design | Reducing tool definition overhead | | Progressive Disclosure | Reveal actions on demand | Managing large action spaces | | Context Offloading | Filesystem storage for context | Context window pressure | | Context Caching | Prompt caching strategies | Cost/latency optimization | | Context Isolation | Sub-agent separation | Long-running or parallel tasks | | Context Evolution | Continual learning | Building agent memories |
1. Computer Access
Components:
- Filesystem: Persistent context storage, state across sessions
- Shell: Execute utilities, CLIs, scripts, or generated code
Implementation:
Agent → Bash Tool → Shell Utilities / CLIs / Scripts
Agent → File Tools → Read / Write / Edit filesystem
2. Multi-Layer Action Space
Action Hierarchy:
Level 1: Tool Calling (agent-visible)
↓
Level 2: Shell Utilities / CLIs (computer-level)
↓
Level 3: Code Execution (generated scripts)
3. Progressive Disclosure
Strategies:
| Layer | Approach |
|:------|:---------|
| Tool Calling | Index definitions, retrieve on demand |
| Shell Utilities | List available utilities in instructions; use --help when needed |
| MCP Servers | Sync descriptions to folder; read full spec only if task requires |
| Skills | YAML frontmatter indexed; full SKILL.md read on demand |
Implementation Pattern:
1. Provide short list of available capabilities
2. Agent reads detailed spec only when task matches
3. Execute with full knowledge loaded just-in-time
4. Context Offloading
Approaches:
- Write old tool results to files
- Store agent trajectories for later retrieval
- Apply summarization only after offloading diminishing returns
Plan File Pattern: Write plan to file → Read periodically to reinforce objectives → Verify work against plan
5. Context Caching
Caching Requirements:
- Stable prefix (system prompt unchanged)
- Append-only message history
- Deterministic serialization (sorted JSON keys)
Anti-Pattern: Mutating history in ways that break cache prefix
6. Context Isolation
Default Approach: Use context: fork
---
name: processing-batch
description: "Processes multiple files in isolated context"
context: fork
allowed-tools: [Read, Write, Bash]
---
Cost: ~3x inline, but FREE as tool call within prompt quota. Use for: Heavy operations (>10 files), parallel processing, isolation needs.
Subagent Alternatives (Use Sparingly)
ONLY when parallelization benefit > 20K token startup cost:
| Scenario | Pattern | Recommendation | |:---------|:--------|:---------------| | Parallelizable tasks | Map-reduce | Use fork unless >50 parallel units | | Long-running tasks | Ralph Loop | Use fork with persistent files | | Independent checks | Parallel reviewers | Use fork for cost efficiency |
The Ralph Loop:
1. Initializer sets up environment (plan file, tracking file)
2. Sub-agents tackle individual tasks from plan
3. Progress communicated via git history
4. Stop hooks verify work after each iteration
5. Repeat until plan satisfied
Benefits:
- Prevents single-agent context saturation
- Enables parallel execution
- Clear isolation boundaries
7. Context Evolution
Evolution Patterns:
| Type | Approach | |:-----|:---------| | Task-specific prompts | Collect trajectories → Score → Reflect on failures → Propose variants | | Memory learning | Distill sessions into diary entries → Reflect → Update instructions | | Skill learning | Reflect over trajectories → Distill reusable procedures → Save as new skills |
Implementation:
Session Log → Reflection → Memory/Skill Update → Context
Quick Reference
For detailed implementations, see:
- references/computer-access.md - Filesystem/shell patterns
- references/action-hierarchy.md - Multi-layer tool design
- references/progressive-disclosure.md - Just-in-time context loading
- references/context-patterns.md - Offload, cache, isolate, evolve
Related Skills:
agent-orchestration- Multi-agent patterns (Orchestrator, Swarm, Hierarchical)context-engineering- Compression, degradation, KV-cache optimizationmemory-systems- Long-term memory architectures