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 xdg/xdg-claude --skill how-to-isolatedgit clone --depth 1 https://github.com/xdg/xdg-claudeWrote 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/xdg/xdg-claude/how-to-isolated)<a href="https://agentmods.dev/skills/xdg/xdg-claude/how-to-isolated"><img src="https://agentmods.dev/badge/skills/xdg/xdg-claude/how-to-isolated/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/xdg/xdg-claude/how-to-isolated"><img src="https://agentmods.dev/badge/skills/xdg/xdg-claude/how-to-isolated.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 | $0.00045 | $0.00721 |
| Opus 5 | $0.00023 | $0.00360 |
| Sonnet 5 | $0.00009 | $0.00144 |
| Haiku 4.5 | $0.00005 | $0.00072 |
Grade A, and why
how-to-isolated 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 12d 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 — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Handling context-heavy tasks
Delegate to the isolated subagent (Agent tool, subagent_type: isolated) when a task's working material is large but the answer is small. The fork absorbs the reading, searching, and reasoning; only the structured writeup comes back.
This is the right tool when no topic-specific subagent applies (commit, code-review, refactor, plan-refactor each have their own — prefer those when they fit). The isolated subagent is the general-purpose fallback with a tighter return-contract than the built-in general-purpose agent.
When to delegate vs. handle inline
Delegate when:
- The task requires reading many files but the conclusion fits in a paragraph (e.g. "where is feature X implemented?", "which callers depend on Y?", "summarize this 2000-line config").
- An exploration might hit dead ends or produce false leads that would clutter the main thread.
- The work is parallelizable with the main task — fire and continue.
- The user explicitly wants something investigated without disturbing the current line of work.
Handle inline (do not delegate) when:
- The task is a single-file read or a one-shot grep. Delegation overhead exceeds the context cost.
- The work is iterative back-and-forth with the user — the subagent runs once and returns.
- A topic-specific subagent fits (commit, code-review, refactor, plan-refactor). Use the specific one.
- The user wants to see the intermediate steps (e.g. they are learning the codebase). Isolation hides the work.
Crafting the delegation prompt
Hand the subagent a clear deliverable, not a process. State the question; let it choose the path. Include any starting points (file paths, symbol names, ticket IDs) the user mentioned, since the fork starts with no conversation context.
Examples:
- User: "find out how rate limiting works in this codebase" → "Investigate how rate limiting is implemented in this codebase. Identify the responsible module(s), the algorithm, and where limits are configured. Report file:line references."
- User: "is feature X still wired up?" → "Determine whether feature X is still reachable from the entry points (HTTP routes, CLI commands, scheduled jobs). Report yes/no with file:line evidence; flag any dead branches you find."
- User: "skim this 5000-line log for what failed" → "Examine the log at . Identify the failure, the immediate cause, and any earlier warnings that look related. Report under 200 words; quote the exact failure lines."
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.
- 12d ago First seen · 43 lines · 45 tokens per session scan A da67ddb73f35
how-to-isolated is a skill published in the GitHub repository xdg/xdg-claude (20 stars, last pushed 4d ago), licensed Apache-2.0. It adds 45 tokens to every session and 721 once invoked, about $0.0002 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 2026-08-30.
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