replying

replying is a skill for Claude Code, Codex from jtsternberg/claude-plugins. It costs 83 tokens per session (1,315 once invoked), scanned A, original, MIT.

A workflow for replying to messages in an AgentMail thread, including replying to the sender, replying to everyone, or forwarding the message. It prepares a reviewable draft before consequential email is sent.

In plain words
What is it for?
Use it to draft and send thread replies or forwards, count reply-all recipients, and handle failed sends without unsafe retries.
Why use it?
It reduces mistakes in irreversible email actions, such as sending to the wrong recipients or accidentally using reply-all.

Skill for Claude CodeCodex

Installs and runs on its own, but its text points at files inside its plugin — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed. Installing the plugin gets both.

Part of the agentmail plugin — 5 skills, 2 hooks shipped together

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/jtsternberg/claude-plugins/replying
Any agent
npx skills add jtsternberg/claude-plugins --skill replying
Clone the repo
git clone --depth 1 https://github.com/jtsternberg/claude-plugins

Made for: Claude Code, Codex.

Or install agentmail, the plugin that ships this one along with the rest of its 5 skills, 2 hooks.

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 replying

README.md
[![agentmods](https://agentmods.dev/badge/skills/jtsternberg/claude-plugins/replying.svg)](https://agentmods.dev/skills/jtsternberg/claude-plugins/replying)
Your own site
<a href="https://agentmods.dev/skills/jtsternberg/claude-plugins/replying"><img src="https://agentmods.dev/badge/skills/jtsternberg/claude-plugins/replying.svg" alt="Measured on agentmods" height="20"></a>
Per session 83 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,315 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 $0.00083 $0.01315
Opus 5 $0.00042 $0.00658
Sonnet 5 $0.00017 $0.00263
Haiku 4.5 $0.00008 $0.00131

Measured 3d ago against content hash e567a469fad2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

replying 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 3d 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.

plugins/agentmail/skills/replying/SKILL.md · 108 lines

How it starts

The opening of the file, as written. The whole thing — 108 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Replying

Answering mail is the one place in this plugin where being slow is correct. Email cannot be recalled and this CLI has no send idempotency, so there is no undo and no safe retry.

Read the reference before you send

Every mechanic — verb choice, the reply-all headcount, drafts, threading, body flags, what to do when a send fails — lives in one file, because relay-work-order and check-mail need the same rules and a second copy would drift from this one.

Codex: substitute the installed plugin directory for the path below.

${CLAUDE_PLUGIN_ROOT}/references/replying.md

Read it before your first send in a session. What follows here is only the part you must not get wrong even if you read nothing else.

The four rules

1. Show, then send. Put the exact to/cc/bcc, the subject, and the full body in front of the user and get explicit confirmation. One confirmation covers one send, not a session. Sends are deliberately absent from allowed-tools so the harness prompts too — that prompt is the feature, and broadening to Bash(agentmail *) would remove the only harness-level guard on an irreversible action.

2. Count before reply-all. inboxes:messages reply-all takes no --to/--cc/--bcc — the API forbids explicit recipients there — so the blast radius is whatever is already on the thread and you cannot trim it at send time. Read the thread, tell the user the number, then send. Cap is 50 across to+cc+bcc.

3. Draft anything the user did not dictate. A draft is a reviewable artifact instead of a claim about what you were about to write, --client-id makes creating it idempotent, and it is AgentMail's own human-in-the-loop recommendation. Show drafts get output, then drafts send after approval.

4. Never retry a failed send. Timeout, 5xx, killed process, unclear error — do not re-run it. Check whether it landed:

agentmail inboxes:messages list --inbox-id <id> --limit 5 --format json > /tmp/am-check.json

Read the full file on GitHub · 108 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 3d ago First seen · 108 lines · 83 tokens per session scan A e567a469fad2

Subscribe to this mod's changes

replying is a skill published in the GitHub repository jtsternberg/claude-plugins (5 stars, last pushed today), licensed MIT. It adds 83 tokens to every session and 1,315 once invoked, about $0.0004 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.