28/28 TESTS PASSING

AI Coding Agent
in Rust

A 2.8MB binary that runs Claude as a full coding agent on your Max subscription. Zero API costs. 7 tools. MCP integration. Ships as a single binary.

2.8MB

Binary Size

28/28

Tests Passing

3,454

Lines of Rust

API Cost

View on GitHub Test Results

claude-agent

$ ./claude-agent

claude-agent v0.1.0 (Rust)

claude-opus-4-6 · effort: High · backend: cli (Claude Max)

7 tools · 11 MCP servers · 11 skills · 5 hooks

agent> write a fizzbuzz in Rust, compile it, run it

[write] /tmp/fizzbuzz.rs

[bash] rustc /tmp/fizzbuzz.rs -o /tmp/fizzbuzz && /tmp/fizzbuzz

1, 2, Fizz, 4, Buzz, Fizz, 7, 8, Fizz, Buzz, 11, Fizz, 13, 14, FizzBuzz...

Done in 21s · 0 API tokens billed

Architecture

11 Layers, 21 Source Files

A complete agent architecture in Rust — from authentication to tool execution, with MCP server integration and hook dispatch.

Inference Engine

Pipes prompts to claude -p via stdin. Strips API key to force Max subscription auth.

src/inference.rs

Tool System

7 built-in tools: bash, read, write, edit, glob, grep, web_fetch. Trait-based dispatch.

src/tools/

MCP Integration

Discovers and connects to MCP servers from Claude config. Extends tool surface dynamically.

src/mcp/

Skills & Hooks

Loads skill definitions and hook configs from ~/.claude/. Dispatches /commands to skills.

src/skills.rs, src/hooks.rs

Permissions

Controls which tools and paths the agent can access. Sandboxing for safe execution.

src/permissions.rs

Context Manager

Tracks conversation history, manages context window, handles /compact.

src/context.rs

Memory System

Persistent memory backed by file system. Reads/writes memory across sessions.

src/memory.rs

Auth Layer

Handles authentication. Strips ANTHROPIC_API_KEY to use subscription auth.

src/auth.rs

Type System

Message types, tool schemas, API response structs. serde-powered (de)serialization.

src/types.rs

Telemetry

Tracks token usage, response times, tool call counts. Session metrics.

src/telemetry.rs

CLI & REPL

Interactive REPL with rustyline. Flag parsing, colored output, status display.

src/main.rs, src/flags.rs

Built-in Tools

7 Native Tools

Each tool is a separate Rust module with async execution, error handling, and structured output.

bash

Execute shell commands

📄

read

Read file contents

✏️

edit

String replacements

📝

write

Create/overwrite files

🔍

glob

Pattern file search

🔎

grep

Content search (regex)

🌐

web_fetch

HTTP requests

Verified

28/28 Tests Passing

Every tool, edge case, and error path tested live against Claude Opus 4.6 on Max subscription.

Simple math (2+2)PASS11s

Bash tool (ls)PASS13s

Read tool (Cargo.toml)PASS17s

Grep tool (async fn)PASS20s

Write + Read chainPASS16s

Multi-step (Python)PASS18s

Built-in commandsPASS<1s

Edit toolPASS39s

Glob tool (*.toml)PASS13s

Empty promptPASS<1s

Error: missing filePASS27s

Special charactersPASS13s

Complex bash (find+wc)PASS25s

3-step tool chainPASS107s

Deep analysisPASS160s

Error propagationPASS12s

Security: rm -rf /REFUSED13s

WebFetch (httpbin)PASS15s

Unicode + emojiPASS31s

Non-zero exit codePASS18s

Read missing filePASS11s

Grep zero matchesPASS17s

Write+compile RustPASS21s

Skill dispatchPASS<1s

Glob + line countPASS22s

Read-edit-verify-undoPASS48s

Bash with sleepPASS17s

Large stdout (500 lines)PASS41s

Why This Matters

Claude Code, But Yours

The first open-source Rust agent that rides your Claude Max subscription for free.

$0 / month

Zero API Cost

Calls claude -p under the hood, which uses your Max subscription's OAuth token. No per-token billing. Run it all day — same flat rate.

FULLY MODIFIABLE

You Own the Code

Unlike Claude Code (closed-source Node.js), this is 3,454 lines of Rust you can read, modify, extend. Add tools, change behavior, strip telemetry — it's yours.

2.8MB BINARY

Single Binary Deploy

No Node.js runtime, no npm install, no dependency tree. One cargo build --release and you have a self-contained binary that starts instantly.

EXTENSIBLE

MCP + Skills + Hooks

Automatically discovers your MCP servers, skills, and hooks from Claude config. Extends the tool surface without modifying the agent.

Feature	Claude Code	claude-agent-rs
Source Code	Closed	Open (Rust)
Binary Size	~200MB (Node.js)	2.8MB
API Cost	Subscription or API	Subscription only ($0 extra)
Custom Tools	MCP only	Native Rust + MCP
Modify Behavior	Config only	Full source access
Startup Time	~2s	<100ms
Embeddable	No	Library or binary

Roadmap

v0.1 → v1.0

5 milestones, 17 tracked issues. View on GitHub

v0.1.0 SHIPPED

Foundation

11 layers, 7 tools, CLI + API backends, MCP discovery, 28/28 tests, crates.io published.

v0.2.0

Streaming & Persistence

SSE streaming, conversation persistence (SQLite), session resume, token tracking.

v0.3.0

Sub-Agents & Parallelism

Agent tool, worktree isolation, task queue, agent-to-agent messaging, concurrency control.

v0.4.0

MCP Client

Full JSON-RPC 2.0 client, stdio transport, tool/resource discovery, health monitoring.

v0.5.0

Cross-Platform

Windows support, Homebrew formula, Docker (scratch), GitHub Actions release pipeline.

v1.0.0

Production Ready

Stable API, plugin system, security audit, OpenTelemetry, docs.rs, semver guarantee.

AI Coding Agentin Rust