Progressive Context Loading (Skills)
The three-level loading pattern Claude Code uses to keep skills lightweight. Level 1: initial search only reads the YAML frontmatter (name + description, ~100 tokens) of every skill. Level 2: once a skill is selected, the full skill.md is loaded (typically 1-2K tokens). Level 3: referenced files (scripts, templates, reference markdown) are loaded only if the skill's instructions explicitly require them. This lets a project carry dozens of skills without blowing context on unused ones.
Key points
- Level 1 reads only YAML frontmatter of every skill in the project
- Level 2 loads the full skill.md only after selection
- Level 3 pulls referenced scripts, templates, and reference files on demand
- Skill.md should stay under 500 lines per Anthropic guidance
- Reference files can live inside the skill folder or anywhere the skill.md path points to
- Enables dozens of skills in one project without proportional token cost
- Mornati's CLI-plus-skill experiment shows why the loading boundary matters: the GitHub CLI skill is cheap when invoked for GitHub work, but expensive if copied into always-loaded files such as
CLAUDE.md[src-041] - On-demand skills let low-frequency tools gain structured command guidance without paying the full Tool Schema Tax of Native MCP [src-041]
- OpenAI's API & Codex Build Hour generalizes the same idea to tool search: GPT-5.4 can discover namespaced tools progressively rather than loading hundreds of tool definitions into context up front [src-084].
- The Workspace Agents session gives the product version: agents can attach multiple skills, while concise skill descriptions and frontmatter-style summaries help the model decide when to load the detailed playbook [src-084].
- [src-094] describes agent skills as the strongest pattern for managing dynamic context: the agent sees lightweight metadata first, loads detailed instructions only when a task matches, and pulls deeper reference material only when needed.
- This pattern lets an agent carry many specialist capabilities without paying the full token cost for every capability in every interaction [src-094].
Related entities
Related concepts
- Claude Code Token Economics
- Claude Code Context Management Discipline
- On-Demand Skill Files
- MCP vs CLI Token Trade-off
- Harness Engineering
- Context Engineering
- Software Factory Model
Source references
- [src-004] Nate Herk cluster — Nate Herk — Claude Code cluster (21 videos)
– Videos referenced: zKBPwDpBfhs, RAZVk5NPNtE
- [src-041] Marco Mornati — "The Future of Agentic Tooling: MCP Servers vs. CLI A Data-Driven Comparison" (2026-04-27)
- [src-084] OpenAI Codex, Workspace Agents, Prompt Caching, and Superintelligence Policy cluster (2026-02-09 to 2026-05-08)
- [src-094] Addy Osmani, Shubham Saboo, Sokratis Kartakis – "The New SDLC With Vibe Coding" (2026-05)
Keep reading from this thread
From 491 indexed pages and articles.
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- Wiki concept GPT-5.4 An OpenAI reasoning model presented in the API & Codex Build Hour as a token-efficient coding and agent model with native computer-use capabilities Related by loading
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