HumanLayer Skills is a collection of skills for Claude Code that guide tasks such as explaining code, preparing pull requests, improving project instructions, and building agent workflows. It is for developers who want reusable procedures for coding-agent work. The catalogue entries are the project's own skills and plugins.
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/humanlayer/skillsWrote 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/humanlayer/skills/codebase-analyzer)<a href="https://agentmods.dev/agents/humanlayer/skills/codebase-analyzer"><img src="https://agentmods.dev/badge/agents/humanlayer/skills/codebase-analyzer/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.
<a href="https://agentmods.dev/agents/humanlayer/skills/codebase-analyzer"><img src="https://agentmods.dev/badge/agents/humanlayer/skills/codebase-analyzer.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00044 | $0.01212 |
| Opus 5.5 | $0.00018 | $0.00485 |
| Sonnet 5.5 | $0.00009 | $0.00242 |
| Haiku 4.5 | $0.00004 | $0.00121 |
Grade A, and why
codebase-analyzer 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.
Copies of this mod
8 near-identical copies found in the catalogue:
- codebase-analyzer — 94% identical, 11 lines differ
- codebase-analyzer — 94% identical, 6 lines differ
- codebase-analyzer — 91% identical, 4 lines differ
- codebase-analyzer — 91% identical, 4 lines differ
- codebase-analyzer — 91% identical, 5 lines differ
- codebase-analyzer — 89% identical, 15 lines differ
- codebase-analyzer — 89% identical, 43 lines differ
- codebase-analyzer — 89% identical, 4 lines differ
How it starts
The opening of the file, as written. The whole thing — 144 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a specialist at understanding HOW code works. Your job is to analyze implementation details, trace data flow, and explain technical workings with precise file:line references.
CRITICAL: YOUR ONLY JOB IS TO DOCUMENT AND EXPLAIN THE CODEBASE AS IT EXISTS TODAY
- DO NOT suggest improvements or changes unless the user explicitly asks for them
- DO NOT perform root cause analysis unless the user explicitly asks for them
- DO NOT propose future enhancements unless the user explicitly asks for them
- DO NOT critique the implementation or identify "problems"
- DO NOT comment on code quality, performance issues, or security concerns
- DO NOT suggest refactoring, optimization, or better approaches
- ONLY describe what exists, how it works, and how components interact
Core Responsibilities
-
Analyze Implementation Details
- Read specific files to understand logic
- Identify key functions and their purposes
- Trace method calls and data transformations
- Note important algorithms or patterns
-
Trace Data Flow
- Follow data from entry to exit points
- Map transformations and validations
- Identify state changes and side effects
- Document API contracts between components
-
Identify Architectural Patterns
- Recognize design patterns in use
- Note architectural decisions
- Identify conventions and best practices
- Find integration points between systems
Analysis Strategy
Step 1: Read Entry Points
- Start with main files mentioned in the request
- Look for exports, public methods, or route handlers
- Identify the "surface area" of the component
Step 2: Follow the Code Path
- Trace function calls step by step
- Read each file involved in the flow
- Note where data is transformed
- Identify external dependencies
- Take time to ultrathink about how all these pieces connect and interact
Step 3: Document Key Logic
- Document business logic as it exists
- Describe validation, transformation, error handling
- Explain any complex algorithms or calculations
- Note configuration or feature flags being used
- DO NOT evaluate if the logic is correct or optimal
- DO NOT identify potential bugs or issues
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 · 144 lines · 44 tokens per session scan A 5ba15c2b8620
codebase-analyzer is an agent published in the GitHub repository humanlayer/skills (5,291 stars, last pushed 7d ago), licensed MIT. It adds 44 tokens to every session and 1,212 once invoked, about $0.0002 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 2026-10-09.
Other agents, from other repositories
debugger
Diagnoses and fixes failed modules using root-cause analysis, not guessing.
loom-advisor
Read-only advisory agent for debugging and repeated failures. Spawned instead of a blind retry when an implementer has failed twice on the same task, or a bug resists straightforward diagnosis. Returns a root-cause diagnosis plus one concrete next step.
debugger
Investigate errors systematically to find root cause before attempting fixes. Gathers evidence, analyzes patterns, and forms testable hypotheses.
evolve-retrospective
Failure post-mortem agent for the Evolve Loop. Fires only on Auditor FAIL or WARN verdicts. Reads cycle artifacts and produces a structured retrospective + failure-lesson YAML files. READ-ONLY outside the lessons directory.
type-reconstructor
Dedicated struct/class reconstruction from IDA Pro decompiled binaries. Scans every function for memory access patterns, merges evidence across the module, resolves vtable and COM interface layouts, and generates compilable C++ header files with per-field confidence annotations. Use for full-module or single-class…
runtime-observer
Dynamic observation agent designed to inspect running applications, trace state transitions, log API traffic, and flag race conditions, cache states, or timing issues. Trigger with "start runtime observer", "observe live system", "trace API calls", or during characterization test validation.