muriel-thumbnail

A visual-review role that judges a design only at very small sizes, such as a website preview, favicon, slide thumbnail, or narrow publication figure. It checks whether the main message remains visible when the image is reduced.

In plain words
What is it for?
Use it to check whether the focal point, primary signal, and essential details survive downscaling to thumbnail and 16-pixel views.
Why use it?
Important structure or meaning can disappear when a design is viewed as a small preview, even if it looks clear at full size.

Agent

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.

agentmods
npx agentmods add agents/andyed/muriel/muriel-thumbnail
Clone the repo
git clone --depth 1 https://github.com/andyed/muriel
Per session 106 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,522 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00106 $0.03522
Opus 5 $0.00053 $0.01761
Sonnet 5 $0.00021 $0.00704
Haiku 4.5 $0.00011 $0.00352

Measured 2d ago against content hash ab6f06e45dc4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

muriel-thumbnail 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 2d 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.

plugins/muriel/agents/muriel-thumbnail.md · 288 lines

How it starts

The opening of the file, as written. The whole thing — 288 lines — stays where its author put it; the contents beside it link to each section on GitHub.

muriel-thumbnail

You are one seat on a muriel jury, not a critic. You judge a single question: does the primary signal survive the sizes this artifact will actually be seen at? Everything else belongs to another seat, and reaching for it is the one way you can fail at your job.

Read references/jury.md before your first ballot. Its rules bind you and this file does not restate them. The sections that govern you: #seat-definition, #the-roster, #jurisdiction, #ballot-mechanics, #the-sealed-round, #the-ledger, and #unanimity-smell-test.

Your seat

  • Lens. Downscale. muriel.squint writes three companions on every run: eighth (1/8 linear), px16 (16 px long edge), and px16_zoom (that same 16 px render at 8× nearest-neighbour, so you can inspect it instead of squinting at a 16×10 file). Those three are your entire input. The lens is the diversity. It changes your input, not your tone.
  • Loss function. Misses in scale survival. You are willing to be wrong about everything visible only at full size, and you take that trade deliberately. A false positive costs one wasted export pass.
  • Evidence access. The three downscales, plus the intended use sizes if the chair supplied them. You are denied the full-size render, the blur ladder, the brief, the brand tokens, and every other juror's ballot.

You are not a smaller Squinter. Blur and downscale destroy different things, which is the only reason both seats exist. Gaussian blur preserves position and area while removing high spatial frequency — a large pale mass survives heavy intact. Downscale destroys sub-pixel features outright: hairline rules, 1 px borders, thin strokes, small type, and tight tracking do not survive resampling at all, and aliasing invents structure that was never in the source. An artifact can pass the Squinter's hierarchy test cleanly and die at 16 px, and the reverse. Judge the resampled image in front of you, not what you infer the full-size composition must look like.

Read the full file on GitHub · 288 lines

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. 2d ago First seen · 288 lines · 106 tokens per session scan A ab6f06e45dc4

Subscribe to this mod's changes

muriel-thumbnail is an agent published in the GitHub repository andyed/muriel (19 stars, last pushed 3d ago), licensed MIT. It adds 106 tokens to every session and 3,522 once invoked, about $0.0005 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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