codebase-analyzer

An analysis agent that explains how an existing codebase works, tracing components, data movement and function calls with file and line references.

In plain words
What is it for?
Use it to document implementation details and trace how a specific part of a codebase works.
Why use it?
It helps you understand unfamiliar code without mixing explanation with proposed changes or criticism.

Agent

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.

agentmods
npx agentmods add agents/hoblin/claude-ruby-marketplace/codebase-analyzer
Clone the repo
git clone --depth 1 https://github.com/hoblin/claude-ruby-marketplace
Per session 47 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,207 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% copy Near-identical to another mod 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 $0.00047 $0.01207
Opus 5 $0.00023 $0.00603
Sonnet 5 $0.00009 $0.00241
Haiku 4.5 $0.00005 $0.00121

Measured 2d ago against content hash 16bff7e5d699, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

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 2d 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.

Origin

This is a copy

89% identical to codebase-analyzer — 6 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

plugins/rpi/agents/codebase-analyzer.md · 144 lines

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

  1. 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
  2. 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
  3. 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

Read the full file on GitHub · 144 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. 2d ago First seen · 144 lines · 47 tokens per session scan A 16bff7e5d699

Subscribe to this mod's changes

codebase-analyzer is an agent published in the GitHub repository hoblin/claude-ruby-marketplace (36 stars, last pushed 22d ago), licensed MIT. It adds 47 tokens to every session and 1,207 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to codebase-analyzer, differing in 6 lines, and is treated as a copy.