reason

reason is a command for Claude Code from pnmcguire480/cairntir. It costs 9 tokens per session (126 once invoked), scanned A, original, MIT.

A command for thinking through a question with information retrieved from stored memory. It starts a session, recalls relevant memories, reasons with them and identifies assumptions for review.

In plain words
What is it for?
Loading relevant memory, explaining the reasoning behind an answer, citing retrieved memory records and identifying issues to examine further.
Why use it?
It gives an agent a defined way to bring in prior context and expose assumptions that may need testing before reaching a conclusion.

Command for Claude Code

Written for Claude Code: $ARGUMENTS substitution.

Part of the cairntir plugin — 2 skills, 3 commands shipped together

Good fit Loading relevant memory, explaining the reasoning behind an answer, citing retrieved memory records and identifying issues to examine further.

Compare 6 commands from other repositories ↓
Install with agentmods
npx agentmods add commands/pnmcguire480/cairntir/reason
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.

Clone the repo
git clone --depth 1 https://github.com/pnmcguire480/cairntir

Made for: Claude Code.

Or install cairntir, the plugin that ships this one along with the rest of its 2 skills, 3 commands.

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 reason

README.md
[![agentmods](https://agentmods.dev/badge/commands/pnmcguire480/cairntir/reason.svg)](https://agentmods.dev/commands/pnmcguire480/cairntir/reason)
Your own site
<a href="https://agentmods.dev/commands/pnmcguire480/cairntir/reason"><img src="https://agentmods.dev/badge/commands/pnmcguire480/cairntir/reason.svg" alt="Measured on agentmods" height="20"></a>
Per session 9 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 126 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 $0.00009 $0.00126
Opus 5 $0.00005 $0.00063
Sonnet 5 $0.00002 $0.00025
Haiku 4.5 $0.00001 $0.00013

Measured 7d ago against content hash 37309c3af30e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

reason 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.

commands/reason.md · 13 lines

What it actually says

Use Cairntir's reason skill to think about the user's question with the help of stored memory.

  1. Call cairntir_session_start to load the 4-layer context for the current wing
  2. Call cairntir_recall to retrieve memories specifically relevant to the question
  3. Reason out loud with the retrieved memories in view — cite drawer ids inline
  4. Propose an answer, and flag any assumptions that should be stress-tested by cairntir_crucible

$ARGUMENTS

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 · 13 lines · 9 tokens per session scan A 37309c3af30e

Subscribe to this mod's changes

reason is a command published in the GitHub repository pnmcguire480/cairntir (2 stars, last pushed yesterday), licensed MIT. It adds 9 tokens to every session and 126 once invoked, about $0.0000 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.