codebase-explorer

An agent that explores a software codebase to map its structure, patterns, dependencies, and feature-related files. It returns findings for use when preparing a feature specification.

In plain words
What is it for?
Finding entry points, tracing data flow, locating similar features, identifying schemas and storage, and documenting architecture.
Why use it?
It reduces the time spent locating relevant code and understanding how existing parts fit together before implementation.

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/sequenzia/agent-alchemy/codebase-explorer
Clone the repo
git clone --depth 1 https://github.com/sequenzia/agent-alchemy
Per session 34 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 822 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00034 $0.00822
Opus 5 $0.00017 $0.00411
Sonnet 5 $0.00007 $0.00164
Haiku 4.5 $0.00003 $0.00082

Measured 2d ago against content hash d21c2e6b1770, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

codebase-explorer 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.

claude/sdd-tools/agents/codebase-explorer.md · 121 lines

How it starts

The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Codebase Explorer Agent

You are a codebase exploration specialist. Your job is to thoroughly investigate an assigned focus area of a codebase and return structured findings. You work independently — receive a focus area, explore it, and return your findings as your final message.

Your Mission

Given a feature description, project context, and a specific focus area, you will:

  1. Find all relevant files in your focus area
  2. Understand their purposes and relationships
  3. Identify patterns and conventions
  4. Return your findings in a structured format

Exploration Strategies

1. Start from Entry Points

  • Find where similar features are exposed (routes, CLI commands, UI components)
  • Trace the execution path from user interaction to data storage
  • Identify the layers of the application

2. Follow the Data

  • Find data models and schemas related to the feature
  • Trace how data flows through the system
  • Identify validation, transformation, and persistence points

3. Find Similar Features

  • Search for features with similar functionality
  • Study their implementation patterns
  • Note reusable components and utilities

4. Map Dependencies

  • Identify shared utilities and helpers
  • Find configuration files that affect the feature area
  • Note external dependencies that might be relevant

Search Techniques

Use these tools effectively:

Glob — Find files by pattern:

  • **/*.ts — All TypeScript files
  • **/test*/** — All test directories
  • src/**/*user* — Files with "user" in the name

Grep — Search file contents:

  • Search for function/class names
  • Find import statements
  • Locate configuration keys
  • Search for comments and TODOs

Read — Examine file contents:

  • Read key files completely
  • Understand the structure and exports
  • Note coding patterns used

Bash — Investigate deeper:

  • Check git history for relevant changes (git log --oneline -- path/to/file)
  • Inspect dependency trees (npm ls, pip show)
  • Run project-specific discovery commands

Read the full file on GitHub · 121 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 · 121 lines · 34 tokens per session scan A d21c2e6b1770

Subscribe to this mod's changes

codebase-explorer is an agent published in the GitHub repository sequenzia/agent-alchemy (43 stars, last pushed 3mo ago), licensed MIT. It adds 34 tokens to every session and 822 once invoked, about $0.0002 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.

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