Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add navendubrajesh/context-management-for-agents --skill context-fundamentalsgit clone --depth 1 https://github.com/navendubrajesh/context-management-for-agentsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/navendubrajesh/context-management-for-agents/context-fundamentals)<a href="https://agentmods.dev/skills/navendubrajesh/context-management-for-agents/context-fundamentals"><img src="https://agentmods.dev/badge/skills/navendubrajesh/context-management-for-agents/context-fundamentals/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/navendubrajesh/context-management-for-agents/context-fundamentals"><img src="https://agentmods.dev/badge/skills/navendubrajesh/context-management-for-agents/context-fundamentals.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00125 | $0.01889 |
| Opus 5 | $0.00063 | $0.00945 |
| Sonnet 5 | $0.00025 | $0.00378 |
| Haiku 4.5 | $0.00013 | $0.00189 |
Grade A, and why
context-fundamentals scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 109 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context Engineering Fundamentals
Context is the complete state available to a language model at inference time: system instructions, tool definitions, retrieved documents, message history, and tool outputs. Context engineering is the discipline of curating the smallest high-signal token set that maximizes the likelihood of desired outcomes.
This skill is the conceptual foundation that every other skill in the collection builds on. It explains what context is, how attention mechanics work, why context quality matters more than quantity, and the mental models needed to interpret every other context-engineering decision. It does not own operational work: debugging attention failures belongs to context-degradation, token-efficiency tactics belong to context-optimization, conversation summarization belongs to context-compression, file-based offloading belongs to filesystem-context, and project-shape decisions belong to project-development.
When to Activate
Activate this skill when the work is conceptual:
- Explaining what context is and how attention mechanics constrain agent behavior.
- Onboarding new contributors who need the mental models before diving into operational skills.
- Reasoning about a context-related design decision from first principles (what does this constraint mean, why does this trade-off exist) before picking a specific tactic.
- Writing or reviewing documentation that needs to ground operational guidance in the underlying mechanics.
Do not activate this skill for operational work. The specialized skills handle the doing:
- Diagnosing lost-in-middle, context poisoning, or attention failures:
context-degradation. - Reducing token cost via masking, partitioning, prefix caching, budgets:
context-optimization. - Compressing a long session into a handoff summary:
context-compression. - Offloading large tool outputs or maintaining a durable scratchpad:
filesystem-context. - Deciding the shape of an LLM project or pipeline:
project-development.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago First seen · 109 lines · 125 tokens per session scan A f2857e63a668
context-fundamentals is a skill published in the GitHub repository navendubrajesh/context-management-for-agents (2 stars, last pushed 2mo ago), licensed MIT. It adds 125 tokens to every session and 1,889 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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