tokio-async-code-review

tokio-async-code-review is a skill for Claude Code from existential-birds/beagle. It costs 91 tokens per session (1,889 once invoked), scanned A, original, Apache-2.0.

A review guide for Rust programs using Tokio, a library that runs asynchronous tasks. It covers runtime setup, task management, channels, synchronization, blocking work, and Tokio feature settings.

In plain words
What is it for?
Use it when reviewing Rust async code that uses Tokio, including spawned tasks, channels, mutexes, timers, runtimes, and async tests.
Why use it?
It helps identify blocked async tasks, unsuitable communication or lock choices, missing runtime features, and configuration that can cause hangs or confusing failures.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the beagle-rust plugin — 11 skills shipped together

Good fit Use it when reviewing Rust async code that uses Tokio, including spawned tasks, channels, mutexes, timers, runtimes, and async tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/existential-birds/beagle/tokio-async-code-review
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 existential-birds/beagle --skill tokio-async-code-review
Clone the repo
git clone --depth 1 https://github.com/existential-birds/beagle

Made for: Claude Code.

Or install beagle-rust, the plugin that ships this one along with the rest of its 11 skills.

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 tokio-async-code-review

README.md
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Your own site
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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.

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Your own site · 80×15
<a href="https://agentmods.dev/skills/existential-birds/beagle/tokio-async-code-review"><img src="https://agentmods.dev/badge/skills/existential-birds/beagle/tokio-async-code-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,889 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 $0.00091 $0.01889
Opus 5.5 $0.00036 $0.00756
Sonnet 5.5 $0.00018 $0.00378
Haiku 4.5 $0.00009 $0.00189

Measured 1mo ago against content hash 38524bfc997c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

tokio-async-code-review 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 1mo 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/beagle-rust/skills/tokio-async-code-review/SKILL.md · 125 lines

How it starts

The opening of the file, as written. The whole thing — 125 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Tokio Async Code Review

Review Workflow

  1. Check Cargo.toml — Note tokio feature flags (full, rt-multi-thread, macros, sync, etc.). Missing features cause confusing compile errors.
  2. Check runtime setup — Is #[tokio::main] or manual runtime construction used? Multi-thread vs current-thread?
  3. Scan for blocking — Search for std::fs, std::net, std::thread::sleep, CPU-heavy loops in async functions.
  4. Check channel usage — Match channel type to communication pattern (mpsc, broadcast, oneshot, watch).
  5. Check sync primitives — Verify correct mutex type, proper guard lifetimes, no deadlock potential.

Gates (objective passes before conclusions)

Complete in order for the review scope. Do not assert Critical or Major until the relevant gate passes.

  1. Dependency surface — Read the crate (and workspace, if inherited) Cargo.toml that supplies tokio. Pass: Written note of tokio version and enabled features, or explicit statement that there is no direct tokio dependency and where it comes from (workspace/path).
  2. Runtime model — Locate runtime construction (#[tokio::main], Runtime::builder, tests, or library with no owned runtime). Pass: One line naming flavor (multi_thread / current_thread / tests-only / none) and where it is defined.
  3. Blocking inventory — Search reviewed paths for blocking APIs (std::fs::, std::net:: without async wrappers, std::thread::sleep, heavy CPU loops in async fn). Pass: Each hit listed as path:line (or tool output excerpt), or explicit “no blocking patterns found in reviewed async code” after the search.
  4. Protocol — Load the review-verification-protocol skill. Pass: Its pass conditions met before any finding is reported (file:line evidence for asserted issues).

Output Format

Report findings as:

[FILE:LINE] ISSUE_TITLE
Severity: Critical | Major | Minor | Informational
Description of the issue and why it matters.

Read the full file on GitHub · 125 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 1mo ago First seen · 125 lines · 91 tokens per session scan A 38524bfc997c

Subscribe to this mod's changes

tokio-async-code-review is a skill published in the GitHub repository existential-birds/beagle (82 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 91 tokens to every session and 1,889 once invoked, about $0.0004 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 2026-09-16.

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