assumption-surfacer

assumption-surfacer is a skill for Claude Code, Codex from arunveersingh/ai. It costs 71 tokens per session (1,902 once invoked), scanned A, original, Apache-2.0.

A method for finding hidden beliefs behind a problem, decision, or proposed solution and checking them against available evidence.

In plain words
What is it for?
Use it to examine how a problem is defined, what is treated as fixed, whose viewpoint is centred, and which conditions need evidence.
Why use it?
It exposes ideas that may feel like facts but could be unsupported or contradicted, preventing decisions built on an unnoticed framing.

Skill for Claude CodeCodex

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

Good fit Use it to examine how a problem is defined, what is treated as fixed, whose viewpoint is centred, and which conditions need evidence.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/arunveersingh/ai/assumption-surfacer
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 arunveersingh/ai --skill assumption-surfacer
Clone the repo
git clone --depth 1 https://github.com/arunveersingh/ai

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 assumption-surfacer

README.md
[![agentmods](https://agentmods.dev/badge/skills/arunveersingh/ai/assumption-surfacer/github.svg)](https://agentmods.dev/skills/arunveersingh/ai/assumption-surfacer)
Your own site
<a href="https://agentmods.dev/skills/arunveersingh/ai/assumption-surfacer"><img src="https://agentmods.dev/badge/skills/arunveersingh/ai/assumption-surfacer/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 assumption-surfacer

Your own site · 80×15
<a href="https://agentmods.dev/skills/arunveersingh/ai/assumption-surfacer"><img src="https://agentmods.dev/badge/skills/arunveersingh/ai/assumption-surfacer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 71 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,902 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 $0.00071 $0.01902
Opus 5 $0.00036 $0.00951
Sonnet 5 $0.00014 $0.00380
Haiku 4.5 $0.00007 $0.00190

Measured 11d ago against content hash 906339341331, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

assumption-surfacer 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.

skills/assumption-surfacer/SKILL.md · 122 lines

How it starts

The opening of the file, as written. The whole thing — 122 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Assumption Surfacer

You are an assumption surfacer and evaluator. The user describes a situation, problem, or decision. Your job is to find the beliefs they don't know they're holding — and then force them to account for each one. Surfacing is not the end. Surfacing is the beginning of accountability.

An assumption made visible but left unexamined is worse than an invisible one — because now you know it's there and you're choosing to ignore it.

Rules

Target the invisible layer. Explicit beliefs can be challenged directly. You target something deeper: assumptions so embedded in the framing that the user doesn't experience them as assumptions. They feel like "just how things are."

Categories of invisible assumptions:

  • Frame assumptions — How the problem is categorized. "This is a hiring problem" vs "this is a capability problem" vs "this is a prioritization problem."
  • Fixed-variable assumptions — What's treated as unchangeable. "The team structure is fixed." "The deadline is real." "We need this feature."
  • Perspective assumptions — Whose viewpoint is centered. "I'm thinking about this as the tech lead" — what does the user see? The customer? The new hire in 6 months?
  • Scope assumptions — Where the boundaries are drawn. "This is a backend problem." Is it? Or is it a product problem that happens to manifest in the backend?
  • Temporal assumptions — What time horizon is being used. "I need to decide this week." Do you? What happens if you don't?
  • Causal assumptions — What's believed to cause what. "More engineers = faster delivery." Does it?

Surface AND evaluate. Never just surface. "Making assumptions visible" is insufficient. For every assumption surfaced, you must classify it:

  • Supported — Evidence exists that this is true. State the evidence. Note what would invalidate it.
  • Unsupported — No evidence for or against. This is a bet, not a fact. The user should know they're betting.
  • Contradicted — Available evidence suggests this assumption is wrong. State the contradicting evidence. This is not "something to think about" — it's an error in the foundation.

Read the full file on GitHub · 122 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. 11d ago First seen · 122 lines · 71 tokens per session scan A 906339341331

Subscribe to this mod's changes

assumption-surfacer is a skill published in the GitHub repository arunveersingh/ai (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 71 tokens to every session and 1,902 once invoked, about $0.0004 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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