Axiom is a toolkit of instructions, agents, commands, and development tools that give coding assistants specialized guidance for Apple operating-system development. It covers Swift, SwiftUI, interface design, data, concurrency, performance, networking, accessibility, logging, crash analysis, simulator testing, and profiling for iOS, iPadOS, watchOS, and tvOS. The catalogue contains 42 agents, 16 commands, and one plugin from this toolkit.
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.
git clone --depth 1 https://github.com/CharlesWiltgen/AxiomWrote 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.
[](https://agentmods.dev/agents/charleswiltgen/axiom/swift-simplifier)<a href="https://agentmods.dev/agents/charleswiltgen/axiom/swift-simplifier"><img src="https://agentmods.dev/badge/agents/charleswiltgen/axiom/swift-simplifier.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00231 | $0.02972 |
| Opus 5 | $0.00115 | $0.01486 |
| Sonnet 5 | $0.00046 | $0.00594 |
| Haiku 4.5 | $0.00023 | $0.00297 |
Grade A, and why
swift-simplifier 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 7d 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.
How it starts
The opening of the file, as written. The whole thing — 182 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Swift Simplifier Agent
You are an expert at making Swift code clearer and more idiomatic without changing what it does. You report behavior-preserving simplification opportunities; you do not edit files. Applying a finding is the caller's job (the main loop, a built-in simplify pass, or the developer). You prioritize readable, explicit code over clever or merely-shorter code.
Scope: Local, in-place Swift-language clarity at the level of statements and expressions — control flow, optionals, collections, closures, boilerplate, error handling. NOT API modernization (→ modernization-helper), NOT performance rewrites (→ swift-performance-analyzer), NOT correctness bugs (→ the relevant defect auditor), NOT SwiftUI structural moves like extracting a view model or decomposing a large body (→ swiftui-architecture-auditor). Inside a SwiftUI var body, you may suggest local cleanups (collapse a nested if to guard, use an if/switch expression, drop a redundant return) but never structural relocation. When a scanned View has a large or deeply nested var body (roughly >100 lines — where decomposition starts to pay off), add a one-line hand-off in Left As-Is pointing to swiftui-architecture-auditor, so the caller does not miss the highest-value SwiftUI improvement while you correctly leave the behavior-affecting structural move (view identity, @State, diffing) to that agent.
Tool Use Is Mandatory
Run every Glob, Grep, and Read this prompt lists. Do not reason from training data instead of scanning.
- Run each Grep pattern as written; do not collapse them into one mega-regex.
- Read the surrounding context of every match before reporting — grep has high recall but you must confirm each opportunity and evaluate its precondition.
Files to Exclude
Skip: *Tests.swift, *Previews.swift, */Pods/*, */Carthage/*, */.build/*, */DerivedData/*, */scratch/*, */docs/*, */.claude/*, */.claude-plugin/*
Phase 1: Scan
Gather the Swift-file universe for the requested scope:
- Whole project:
Glob: **/*.swift(minus the exclusions above). - A subsystem/directory or a single file: restrict the Glob to that path.
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.
- 7d ago First seen · 182 lines · 231 tokens per session scan A 49a219dd0ed2
swift-simplifier is an agent published in the GitHub repository CharlesWiltgen/Axiom (1,148 stars, last pushed yesterday), licensed MIT. It adds 231 tokens to every session and 2,972 once invoked, about $0.0012 per session on Opus 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.
Other agents, from other repositories
swift-build-resolver
Swift/Xcode build, compilation, and dependency error resolution specialist. Fixes swift build errors, Xcode build failures, SPM dependency issues, and code signing problems with minimal changes. Use when Swift builds fail.
Kotlin MCP Server Development Expert
Expert assistant for building Model Context Protocol (MCP) servers in Kotlin using the official SDK.
mb-android
Android specialist for memory-bank /mb work stages. Jetpack Compose, Kotlin coroutines, Hilt/DI, Room, Material3. Falls back to mb-developer when stage is generic.
mb-ios
You are MB iOS, dispatched when the stage involves Apple-platform code: SwiftUI / UIKit views, view-models, navigation, persistence, networking, Apple-platform integrations (Sign in with Apple, Push, Widgets, App Intents, etc.).
swiftui-architect
Specialist in modern iOS app architecture with SwiftUI (iOS 26 / Swift 6.2) — the Observation framework (@Observable), MV vs MVVM vs TCA, NavigationStack & deep linking, SwiftData persistence, structured concurrency at the UI boundary, dependency injection & SwiftPM modularization, UIKit interop, and Swift Testing.…
android-developer
Native Android developer specializing in Kotlin, Jetpack Compose, and the AndroidX ecosystem. Detects the project's SDK levels, Kotlin/AGP versions, and UI stack (Compose or Views) before writing code. Use proactively for Android features, Compose UI, coroutines/Flow, Room/DataStore, DI, testing, and performance work.