eng-plugin-authoring

eng-plugin-authoring is a skill for Claude Code, Codex from oodaris/autocodex. It costs 18 tokens per session (252 once invoked), scanned A, original, MIT.

A guide for building external autocodex add-ons that communicate through JSON-RPC, a standard format for sending structured requests and responses between programs.

In plain words
What is it for?
Use it to create or update a plugin manifest, implement the connection and request loop, define capability schemas, and add usage documentation.
Why use it?
It identifies the files, connection steps, and input/output definitions required for an add-on to load and answer requests.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create or update a plugin manifest, implement the connection and request loop, define capability schemas, and add usage documentation.

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Install with agentmods
npx agentmods add skills/oodaris/autocodex/eng-plugin-authoring
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.

Any agent
npx skills add oodaris/autocodex --skill eng-plugin-authoring
Clone the repo
git clone --depth 1 https://github.com/oodaris/autocodex

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for eng-plugin-authoring

README.md
[![agentmods](https://agentmods.dev/badge/skills/oodaris/autocodex/eng-plugin-authoring.svg)](https://agentmods.dev/skills/oodaris/autocodex/eng-plugin-authoring)
Your own site
<a href="https://agentmods.dev/skills/oodaris/autocodex/eng-plugin-authoring"><img src="https://agentmods.dev/badge/skills/oodaris/autocodex/eng-plugin-authoring.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 252 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00018 $0.00252
Opus 5 $0.00009 $0.00126
Sonnet 5 $0.00004 $0.00050
Haiku 4.5 $0.00002 $0.00025

Measured 8d ago against content hash 53945e9426cf, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

eng-plugin-authoring 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 8d 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.

skills/eng-plugin-authoring/SKILL.md · 47 lines

What it actually says

Plugin Authoring

Repo anchors (autocodex)

  • PLUGINS_PATH: plugins/
  • DOCS_PATH: docs/plugins/README.md

When to use

  • Creating or updating an autocodex plugin.

Preconditions

  • You know the capability inputs/outputs.

Inputs to confirm

  • Capability name and schemas
  • Transport (jsonrpc for v1)

Required artifacts

  • plugin.yaml manifest
  • Executable plugin binary/script
  • Example invocation

Quick path

  • Write manifest.
  • Implement handshake and JSON-RPC loop.
  • Add a sample invocation.

Steps

  1. Define capability input/output schema.
  2. Implement handshake and request loop.
  3. Add usage docs.

Failure modes and responses

  • Handshake missing: plugin will fail to load.
  • Capability mismatch: host rejects the request.

Definition of done

  • Plugin loads and responds to a capability call.

Example (minimal)

  • Capability: summarize with {text:string} input.
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. 8d ago First seen · 47 lines · 18 tokens per session scan A 53945e9426cf

Subscribe to this mod's changes

eng-plugin-authoring is a skill published in the GitHub repository oodaris/autocodex (16 stars, last pushed 6mo ago), licensed MIT. It adds 18 tokens to every session and 252 once invoked, about $0.0001 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.