explore-codebase

A read-only way to explore an unfamiliar codebase, or software project, by searching files and tracing how code connects. It can follow calls, routes, dependencies, and service boundaries where supported.

In plain words
What is it for?
Use it to locate code, trace request paths, find usages and patterns, inspect dependencies, and assess the likely impact of a change.
Why use it?
It reduces the time spent guessing which files or functions matter before making a change. It also helps reveal how a change in one part of a project may affect another.

Skill for Claude CodeCodex

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 skills/humanbean17/jrag/explore-codebase
Any agent
npx skills add HumanBean17/jrag --skill explore-codebase
Clone the repo
git clone --depth 1 https://github.com/HumanBean17/jrag

Made for: Claude Code, Codex.

Per session 117 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,226 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 $0.00117 $0.03226
Opus 5 $0.00059 $0.01613
Sonnet 5 $0.00023 $0.00645
Haiku 4.5 $0.00012 $0.00323

Measured yesterday against content hash b83cf57880c4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

explore-codebase 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 yesterday.

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.

skills/explore-codebase/SKILL.md · 166 lines

How it starts

The opening of the file, as written. The whole thing — 166 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/explore-codebase — Universal codebase exploration

Read-only exploration combining jrag graph navigation with broad file-system search.

Use any time you must search, locate, navigate, or explore. Do NOT use when the answer is already in context or for a single known file — read it directly.

Core Principles

  1. Read-only. Never edit, write, or modify any file.
  2. Smallest sufficient tool. Pick the lightest tool that answers the question.
  3. Stop when answered. Don't prefetch unrelated subgraphs or directories.

Tool Inventory

  • Graph (jrag MCP): search, find, describe, neighbors, resolve. Node kinds: Symbol (types/methods), Route (HTTP/messaging entry points), Client (outbound HTTP), Producer (outbound async). Indexed content: Java + SQL + YAML (table: java, sql, yaml, all).
  • File-system: Grep (content/regex), Glob (name/path patterns), Read (offset/limit for large files).
  • Other: Bash (read-only: git log, git blame, ls, find), WebSearch/WebFetch.

Decision Framework

User asks… First step Follow-up
Identifier-shaped string resolve (+ optional hint_kind) describeneighbors
Fuzzy / NL "where is X" search describeneighbors
All controllers in service S find(kind="symbol", filter={"microservice":"S","role":"CONTROLLER"}) neighbors CALLS/EXPOSES
Interfaces in service S find(..., filter={"microservice":"S","symbol_kind":"interface"}) neighbors/describe
HTTP / messaging entry points find(kind="route", filter={…}) describe
Outbound HTTP clients find(kind="client", filter={…}) neighbors(..., "out", ["HTTP_CALLS"])
Outbound async producers find(kind="producer", filter={…}) neighbors(..., "out", ["ASYNC_CALLS"])
Who calls method M? id via resolve/find/search neighbors(ids, "in", ["CALLS"])
What does M call? same neighbors(ids, "out", ["CALLS"])
Who hits this route? route id neighbors(ids, "in", ["HTTP_CALLS","ASYNC_CALLS","EXPOSES"])
Handler for route route id neighbors(ids, "in", ["EXPOSES"])
Who implements/injects T? type symbol id neighbors(ids, "in", ["IMPLEMENTS"]) or ["INJECTS"]
Impact of changing X? bounded neighbors in loop (CALLS, INJECTS, …) Grep fallback
Find files / text Glob / Grep Read
Who changed X and when? Bash: git log/git blame
"How is this configured?" Glob + Grep; search(query=…, table="yaml") Read sections

Read the full file on GitHub · 166 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. yesterday First seen · 166 lines · 117 tokens per session scan A b83cf57880c4

Subscribe to this mod's changes

explore-codebase is a skill published in the GitHub repository HumanBean17/jrag (9 stars, last pushed 6d ago), licensed MIT. It adds 117 tokens to every session and 3,226 once invoked, about $0.0006 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 2026-08-31.

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