preview-first-large-output-messages

preview-first-large-output-messages is a skill for Claude Code, Codex from ychampion/cskill-agents. It costs 33 tokens per session (414 once invoked), scanned A, original, MIT.

A message format for large saved tool results that shows the saved file reference and an initial preview before the rest is truncated. The preview is taken from the saved content.

In plain words
What is it for?
Use it when tool output is too large to display inline but must remain available for later inspection.
Why use it?
It lets users see what an output contains while making clear that the complete result remains available in the saved artifact.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when tool output is too large to display inline but must remain available for later inspection.

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Install with agentmods
npx agentmods add skills/ychampion/cskill-agents/preview-first-large-output-messages
Install

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.

Any agent
npx skills add ychampion/cskill-agents --skill preview-first-large-output-messages
Clone the repo
git clone --depth 1 https://github.com/ychampion/cskill-agents

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for preview-first-large-output-messages

README.md
[![agentmods](https://agentmods.dev/badge/skills/ychampion/cskill-agents/preview-first-large-output-messages/github.svg)](https://agentmods.dev/skills/ychampion/cskill-agents/preview-first-large-output-messages)
Your own site
<a href="https://agentmods.dev/skills/ychampion/cskill-agents/preview-first-large-output-messages"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/preview-first-large-output-messages/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.

agentmods 80×15 button for preview-first-large-output-messages

Your own site · 80×15
<a href="https://agentmods.dev/skills/ychampion/cskill-agents/preview-first-large-output-messages"><img src="https://agentmods.dev/badge/skills/ychampion/cskill-agents/preview-first-large-output-messages.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 414 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00033 $0.00414
Opus 5 $0.00016 $0.00207
Sonnet 5 $0.00007 $0.00083
Haiku 4.5 $0.00003 $0.00041

Measured 7d ago against content hash 3d2c8df4ad42, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

preview-first-large-output-messages 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 7d 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.

agents/claude-code/skills/preview-first-large-output-messages/SKILL.md · 29 lines

What it actually says

SKILL: Preview-First Large Output Messages

Domain: messaging
Trigger: Apply whenever a persisted tool result response must include a preview so the model sees the start of the output along with the saved artifact reference.
Source Pattern: Distilled from reviewed large-result persistence and preview UX implementations.

Core Method

When tool output is too large to show inline, persist the full artifact first and then render a response that leads with the saved-file reference plus a short preview from the beginning of the content. Build the preview from the stored artifact rather than regenerating it from a second formatting path, so what the user sees matches what was actually saved. Include enough metadata to show that the preview is partial and that the full artifact remains available for later reading.

Key Rules

  • Always begin the visible message with the persisted-file reference and the preview block so readers know the full output was preserved.
  • Generate the preview from the saved content so the preview equals the displayed portion; don’t replay the original stream twice.
  • Include an explicit partial-output marker when the original content exceeded the preview length so downstream renderers know the preview is incomplete.
  • Persisted metadata should note whether the content is JSON so future reads interpret the file correctly.

Example Application

When a tool returns a 200 KB JSON dump, store it as tool-results/<id>.json, then emit a message that points to that file and shows the first couple kilobytes as a preview so the user immediately understands what was returned.

Anti-Patterns (What NOT to do)

  • Don’t reinject the entire persisted file into the preview; keep the preview length bound to the configured slice.
  • Don’t omit the persisted-file reference; without it, the preview becomes a dead end instead of a usable large-output contract.
Changes

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.

  1. 7d ago First seen · 29 lines · 33 tokens per session scan A 3d2c8df4ad42

Subscribe to this mod's changes

preview-first-large-output-messages is a skill published in the GitHub repository ychampion/cskill-agents (36 stars, last pushed 5mo ago), licensed MIT. It adds 33 tokens to every session and 414 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 2026-09-03.