writing-specs

writing-specs is a skill for Claude Code, Codex from JetBrains/thinkrail. It costs 59 tokens per session (686 once invoked), scanned A, original, Apache-2.0.

A shared standard for writing short, honest software specifications. It covers goals, requirements, architecture, and module boundaries.

In plain words
What is it for?
Use it when drafting or revising a specification that another developer or coding agent will rely on.
Why use it?
It keeps specifications focused on decisions and confirmed information, without turning them into long file inventories or hiding uncertainty.

Skill for Claude CodeCodex ✓ vendor

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

Good fit Use it when drafting or revising a specification that another developer or coding agent will rely on.

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Install with agentmods
npx agentmods add skills/jetbrains/thinkrail/writing-specs
About the project

JetBrains/thinkrail is a desktop and mobile client that embeds the pi coding agent inside an interface for editing code and managing development workspaces. Developers use it to work on Git repositories through separate worktrees, a Monaco editor, terminals, Git views, specifications, and concurrent agent sessions. The catalogue entries are skills and instructions for its agent-based development workflow.

JetBrains/thinkrail · 988 stars · on GitHub · thinkrail.ai

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 JetBrains/thinkrail --skill writing-specs
Clone the repo
git clone --depth 1 https://github.com/JetBrains/thinkrail

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 writing-specs

README.md
[![agentmods](https://agentmods.dev/badge/skills/jetbrains/thinkrail/writing-specs/github.svg)](https://agentmods.dev/skills/jetbrains/thinkrail/writing-specs)
Your own site
<a href="https://agentmods.dev/skills/jetbrains/thinkrail/writing-specs"><img src="https://agentmods.dev/badge/skills/jetbrains/thinkrail/writing-specs/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 writing-specs

Your own site · 80×15
<a href="https://agentmods.dev/skills/jetbrains/thinkrail/writing-specs"><img src="https://agentmods.dev/badge/skills/jetbrains/thinkrail/writing-specs.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 686 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00059 $0.00686
Opus 5.5 $0.00024 $0.00274
Sonnet 5.5 $0.00012 $0.00137
Haiku 4.5 $0.00006 $0.00069

Measured 23d ago against content hash 3d5ab7144d0d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

writing-specs 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 23d 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.

packages/pi-thinkrail-workflow/skills/writing-specs/SKILL.md · 53 lines

How it starts

The opening of the file, as written. The whole thing — 53 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Writing Specs

The workflow family's shared bar for every spec a workflow produces: short, honest, on-rails. Process skills name this concept at the steps that draft or revise specs; what to draft and when stays with the referencing skill. Graph mechanics — frontmatter, link kinds, the spec_* tools — are the spec-graph skill's ground; this concept carries the quality bar the family holds on top of them, and is where the family's rules for specs and the spec graph accrue.

Short

  • Small enough to read in one sitting. Target signal, not completeness.
  • Explain intent, not inventory: what the thing is for, what it owns, where its boundary runs — never a file listing or a restatement of the code.

Honest

  • Only settled content appears. Never pad with [TBD] or placeholder sections — a section that hasn't been settled simply doesn't exist yet.
  • Anything inferred rather than confirmed is marked unconfirmed, inline, where it stands.
  • New and inferred specs are status: draft until the user has reviewed them — the flip out of draft follows the user's review, never the drafting agent's own judgment. A reviewed durable spec goes active, never done: it stays in force and evolves with the project.

On-rails

  • High-signal enough that a future agent (or human) lands on the decisions without re-deriving them.
  • The spec is the only home for rationale: decisions, invariants, trade-offs, and bug post-mortems are recorded here, never as code comments — a rationale paragraph found in code is content to promote into the owning spec, leaving at most a one-line pointer where misediting would silently break something.
  • Say each thing once: link by id instead of restating; the dependency edges between sibling modules live in the parent's spec, not in each leaf.
  • One spec per genuine boundary — not per directory, not per file.

The goal doc describes the product, not a plan

goal-and-requirements is the living record of what the product is and why: its goal, problem, audience, capabilities, and non-goals, plus any durable principles.

Read the full file on GitHub · 53 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. 23d ago Changed · +15 lines 3d5ab7144d0d
  2. 1mo ago First seen · 38 lines · 59 tokens per session scan A 2b827c405fb8

Subscribe to this mod's changes

writing-specs is a skill published in the GitHub repository JetBrains/thinkrail (988 stars, last pushed today), licensed Apache-2.0. It adds 59 tokens to every session and 686 once invoked, about $0.0002 per session on Opus 5.5. 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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