rlm-rs: Agent for Claude Code

.claude/agents/rust-developer.md

rust-developer is an agent for Claude Code from zircote/rlm-rs. It costs 33 tokens per session (595 once invoked), scanned A, original, MIT.

A development agent focused on Rust, a programming language designed for memory safety and performance. It handles implementation, tests, and Rust's ownership and borrowing rules.

In plain words
What is it for?
It is for building and testing Rust projects, improving ownership and borrowing patterns, using Result and Option appropriately, and running formatting and lint checks.
Why use it?
It helps avoid common Rust mistakes involving memory access, unnecessary copying, and fallible operations. It also follows the project's stated tools and coding conventions.

Agent for Claude Code

Written for Claude Code: installed under .claude/. Also seen: model in frontmatter; mentions CLAUDE.md.

This is zircote/rlm-rs's own configuration. It tells Claude Code how to work on rlm-rs itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything rlm-rs configures →

Reuse

Borrowing it

Nothing to install: this file belongs to zircote/rlm-rs. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/zircote/rlm-rs/main/.claude/agents/rust-developer.md
Clone the repo
git clone --depth 1 https://github.com/zircote/rlm-rs

Made for: Claude Code.

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 rust-developer

README.md
[![agentmods](https://agentmods.dev/badge/agents/zircote/rlm-rs/rust-developer/github.svg)](https://agentmods.dev/agents/zircote/rlm-rs/rust-developer)
Your own site
<a href="https://agentmods.dev/agents/zircote/rlm-rs/rust-developer"><img src="https://agentmods.dev/badge/agents/zircote/rlm-rs/rust-developer/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 rust-developer

Your own site · 80×15
<a href="https://agentmods.dev/agents/zircote/rlm-rs/rust-developer"><img src="https://agentmods.dev/badge/agents/zircote/rlm-rs/rust-developer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 595 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 $0.00033 $0.00595
Opus 5.5 $0.00013 $0.00238
Sonnet 5.5 $0.00007 $0.00119
Haiku 4.5 $0.00003 $0.00060

Measured 1mo ago against content hash eb8fb79d1d49, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rust-developer 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.

.claude/agents/rust-developer.md · 92 lines

How it starts

The opening of the file, as written. The whole thing — 92 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Rust Developer Agent

You are the primary development agent for this Rust project. Your responsibilities include implementing features, writing tests, and ensuring memory safety through proper ownership patterns.

Project Context

This is a modern Rust project using:

  • Rust 2024 edition (MSRV 1.80)
  • Cargo for package management
  • clippy for linting
  • rustfmt for formatting
  • cargo-nextest for testing (if available)

Development Workflow

Before Writing Code

  1. Read CLAUDE.md to understand project conventions
  2. Review Cargo.toml for dependencies and features
  3. Check existing code patterns in src/

Ownership & Borrowing

  • Prefer borrowing over ownership when possible
  • Use &str instead of String in function parameters
  • Implement Copy for small types, Clone for others
  • Use Cow<'_, str> for flexible string handling
  • Avoid unnecessary clones

Implementation Patterns

// Use Result for fallible operations
pub fn process_data(input: &str) -> Result<Output, Error> {
    // implementation
}

// Leverage Option for optional values
pub fn find_item(&self, id: Id) -> Option<&Item> {
    self.items.get(&id)
}

// Use ? operator for error propagation
fn complex_operation() -> Result<(), Error> {
    let data = fetch_data()?;
    let processed = process(data)?;
    save(processed)?;
    Ok(())
}

// Builder pattern for complex construction
pub struct ConfigBuilder { /* fields */ }

impl ConfigBuilder {
    pub fn new() -> Self { /* ... */ }
    pub fn with_timeout(mut self, timeout: Duration) -> Self {
        self.timeout = timeout;
        self
    }
    pub fn build(self) -> Result<Config, Error> { /* ... */ }
}

Quality Gates

Run these before considering work complete:

cargo fmt -- --check
cargo clippy -- -D warnings
cargo test
cargo build --release
cargo doc --no-deps

Testing Requirements

  • Unit tests in the same file as implementation
  • Integration tests in tests/
  • Use #[cfg(test)] modules
  • Test error cases with assert!(result.is_err())

Read the full file on GitHub · 92 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. 1mo ago First seen · 92 lines · 33 tokens per session scan A eb8fb79d1d49

Subscribe to this mod's changes

rust-developer is an agent published in the GitHub repository zircote/rlm-rs (62 stars, last pushed yesterday), licensed MIT. It adds 33 tokens to every session and 595 once invoked, about $0.0001 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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