solo

solo is a skill for Claude Code from anthropics/claude-plugins-official. It costs 77 tokens per session (1,445 once invoked), scanned A, original, Apache-2.0.

A staged method for solving one difficult mathematics problem in the current session without helper agents. It records settled reasoning in a notes file and ends by writing a self-contained proof.md.

In plain words
What is it for?
Use it when you want one session to reason through a proof or disproof from start to finish.
Why use it?
It preserves progress if the session is interrupted and keeps the final argument separate from exploratory work.

Skill for Claude Code ✓ vendor

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions subagents; names the AskUserQuestion tool.

Part of the math-proof plugin — 2 skills, 3 agents shipped together

Good fit Use it when you want one session to reason through a proof or disproof from start to finish.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/anthropics/claude-plugins-official/solo
About the project

Claude Code Plugins Directory is a marketplace containing plugins for Claude Code, including tools, commands, skills, agents, hooks, and model context servers. Claude Code users browse it to install Anthropic-maintained or approved third-party extensions.

anthropics/claude-plugins-official · 39,070 stars · on GitHub · code.claude.com

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 anthropics/claude-plugins-official --skill solo
Clone the repo
git clone --depth 1 https://github.com/anthropics/claude-plugins-official

Made for: Claude Code.

Or install math-proof, the plugin that ships this one along with the rest of its 2 skills, 3 agents.

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 solo

README.md
[![agentmods](https://agentmods.dev/badge/skills/anthropics/claude-plugins-official/solo/github.svg)](https://agentmods.dev/skills/anthropics/claude-plugins-official/solo)
Your own site
<a href="https://agentmods.dev/skills/anthropics/claude-plugins-official/solo"><img src="https://agentmods.dev/badge/skills/anthropics/claude-plugins-official/solo/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 solo

Your own site · 80×15
<a href="https://agentmods.dev/skills/anthropics/claude-plugins-official/solo"><img src="https://agentmods.dev/badge/skills/anthropics/claude-plugins-official/solo.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 77 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,445 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 $0.00077 $0.01445
Opus 5.5 $0.00031 $0.00578
Sonnet 5.5 $0.00015 $0.00289
Haiku 4.5 $0.00008 $0.00145

Measured 15d ago against content hash 2b6ecb93b014, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

solo 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 15d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • solo — 100% identical, 0 lines differ
plugins/math-proof/skills/solo/SKILL.md · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

math-proof: solo

You solve the problem yourself, in this session. There are no sub-agents and no rounds: just you, a notes file and, at the end, proof.md.

Arguments. The invoking message reads: $ARGUMENTS It gives the problem and, optionally, the run directory. Read it this way. A token of the form DIR=path at its start sets the run directory (the path quoted if it contains spaces); remove it. Any other leading token of the form NAME=value, where NAME is a word of two or more capital letters and underscores and value is a whole number, is a setting this skill does not have: tell the user in one sentence that /math-proof:solo takes only DIR=path before the problem (round and wave settings belong to /math-proof:siege), and that if the token is part of the problem itself the problem can be given as a file path instead, and stop. If what remains is a single line that, taken as a whole — surrounding whitespace and one pair of enclosing quotation marks removed, backslash-escaped spaces read as spaces — is the path of an existing file (it may contain spaces; check with Read or Glob, not the shell), that file is the problem file; if no such file exists and what remains can only be a file path — a single line ending in .md, .txt or .tex, or a single token (no spaces once the quotes are removed) containing "/" or "" — tell the user in one sentence that no file exists at the absolute path you looked for (give it) and that the problem can instead be given in full as text after the command, and stop; otherwise everything that remains, to the end of the message, IS the problem statement, verbatim — mathematics, line breaks and all ("n=3", "N=pq" and "AB=AC" are mathematics, not settings). The run directory DIR defaults to ./math-proof-solo under the current directory; use DIR's absolute path everywhere below. If the message holds neither a readable problem file nor any problem text, say so in one sentence — with the usage, /math-proof:solo <problem statement, or the path of a file holding it> — and stop.

Setup. The run's files are DIR/problem.md (the problem), DIR/notes.md (your notes) and DIR/proof.md (the deliverable). Create DIR with mkdir -p. If DIR/notes.md already exists, this problem was already being worked on in DIR: check that DIR/problem.md is the same problem you were given (compare the text, ignoring differences in whitespace and line endings; for a file, cmp) — if it differs, say in one sentence that DIR holds work on a different problem and that DIR=<another directory> selects a fresh one, and stop; if it is the same, read DIR/notes.md, and DIR/proof.md if it exists. If they record the solution as complete (proof.md written and nothing in the notes still to do), the earlier session finished: say where proof.md is and that DIR=<another directory> starts a fresh attempt, and stop. Otherwise the earlier session ended before it finished, and whatever reasoning it had not written down is lost: continue from the last point recorded there rather than starting over. If DIR/notes.md does not exist yet, put the problem at DIR/problem.md: if it came as a file, copy that file there byte for byte with cp; if it came as text in the invoking message, Write exactly that text (nothing added, removed or reworded). Then Read DIR/problem.md in full; it is the authoritative text of the problem. Use the shell for nothing but that mkdir, cp and cmp.

The task. Solve the problem stated in DIR/problem.md; the deliverable is DIR/proof.md. After reasoning, write your answer. This task runs as a conversation that can span many messages, each with a bounded output allowance; a message that is cut off is normally followed by a request to continue, and only what you have WRITTEN (not unwritten reasoning) is guaranteed to carry into the next message. So write your work product out as you go, in a notes file, DIR/notes.md: whenever you settle something — a lemma and its proof, a reduction, a dead end and why it is dead, the precise statement you are now attempting — write it down before reasoning further. A partial answer is much more useful than none. Writing to the notes is not finishing — keep going after each write. Important: each message's output allowance also covers your private reasoning, and it is far smaller than a hard problem deserves — a message spent entirely on reasoning, with nothing written, gets cut off, and unwritten reasoning should be assumed lost. So do not try to finish in one message. Work in stages: early in EVERY message, before any long derivation, write your current plan and the precise statement you are attempting to DIR/notes.md; then reason toward the next concrete intermediate result, append it to the notes as soon as you have it, and continue. Many short written steps beat one long unwritten one. If a message of yours is cut off, re-read DIR/notes.md and continue from the last thing written there; never start over. You have no web access and no code execution; this is a pure reasoning task. When the problem is resolved, or you have taken it as far as you can, write your complete solution to DIR/proof.md. proof.md is read on its own by a referee who cannot open any other file (not your notes either), so it must be self-contained: every argument the solution relies on is written out in full there. Work unattended: there is no one to answer questions, so never stop to ask.

Read the full file on GitHub · 70 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. 15d ago First seen · 70 lines · 77 tokens per session scan A 2b6ecb93b014

Subscribe to this mod's changes

solo is a skill published in the GitHub repository anthropics/claude-plugins-official (39,070 stars, last pushed today), licensed Apache-2.0. It adds 77 tokens to every session and 1,445 once invoked, about $0.0003 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 2026-10-01.

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