witan-code

A code map that tracks where functions, classes, modules, and their connections are defined across one or more repositories.

In plain words
What is it for?
Use it to find symbol definitions, callers, references, and likely breakage, or to trace shared environment variables, web endpoints, packages, and services between repositories.
Why use it?
It answers structural questions more reliably than searching text, such as what calls a function or what could be affected by a change.

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/mitodl/agent-kit/witan-code
Any agent
npx skills add mitodl/agent-kit --skill witan-code
Clone the repo
git clone --depth 1 https://github.com/mitodl/agent-kit

Made for: Claude Code, Codex.

Per session 120 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,466 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 $0.00120 $0.01466
Opus 5 $0.00060 $0.00733
Sonnet 5 $0.00024 $0.00293
Haiku 4.5 $0.00012 $0.00147

Measured yesterday against content hash 781041fd2123, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

witan-code 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.

mcp/servers/witan-code/witan_code/skills/witan-code/SKILL.md · 117 lines

How it starts

The opening of the file, as written. The whole thing — 117 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Code Graph

A per-repo, tree-sitter-derived graph of symbols (functions, methods, classes, modules) and their relationships (Calls, References, Imports, Inherits), plus a cross-repo bridge linking services through shared contracts (env vars, HTTP endpoints, packages, deployments). Indexing is automatic — a SessionStart hook seeds/refreshes the whole repo in the background, and a PostToolUse hook incrementally reindexes each file you edit — so you rarely need to invoke the CLI yourself.

When to use this vs. grep / the Explore agent

Reach for code_* tools when the question is structural, not textual:

  • "Where is Service.run defined?" → code_find_definition / code_search_symbol
  • "What calls this function, anywhere in the repo?" → code_callers / code_find_references
  • "If I change this, what breaks?" (transitive blast radius) → code_impact
  • "What symbols does this file define?" → code_symbols_in_file
  • "Which other repo reads this env var / calls this endpoint / imports this package?" → code_interface_consumers / code_interface_providers / code_cross_repo_impact

Grep is still the right tool for literal string/comment searches, one-off text matches, or a repo with no code graph yet. The two are complementary: grep finds text; code_* tools resolve symbols and their relationships, which grep cannot do (it can't tell you a function's transitive callers or which service consumes an endpoint another service serves).

Caveat: Calls/References/Imports/Inherits edges are heuristic (syntactic name resolution, not a true call graph) — treat impact/caller results as a high-recall starting point, not a verified answer. Defines and Contains are exact.

On invocation

  • No args → Check readiness, then show the tool reference below.
  • reindex → call the code_reindex MCP tool (or witan-code reindex if running the CLI directly) to force a full rebuild of the current repo, ignoring content hashes. Use when the graph looks stale and you don't want to wait for the incremental hooks to catch up.

Read the full file on GitHub · 117 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 · 117 lines · 120 tokens per session scan A 781041fd2123

Subscribe to this mod's changes

witan-code is a skill published in the GitHub repository mitodl/agent-kit (2 stars, last pushed 3d ago), licensed BSD-3-Clause. It adds 120 tokens to every session and 1,466 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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