agent-inbox

agent-inbox is a skill for Claude Code, Codex from gsd-build/agent-inbox. It costs 54 tokens per session (846 once invoked), scanned A, original, MIT.

A temporary email inbox service for testing software flows that send verification or confirmation messages. It uses disposable inbox providers and can extract links from received emails.

In plain words
What is it for?
Use it to create test email addresses, receive messages, wait for matching emails, extract verification links, complete email verification, and clean up inboxes afterward.
Why use it?
Authentication tests often need a real inbox to receive signup, password, or account-confirmation messages. Temporary inboxes avoid using personal or permanent test accounts.

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/gsd-build/agent-inbox/skill
Any agent
npx skills add gsd-build/agent-inbox --skill skill
Clone the repo
git clone --depth 1 https://github.com/gsd-build/agent-inbox

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 agent-inbox

README.md
[![agentmods](https://agentmods.dev/badge/skills/gsd-build/agent-inbox/skill.svg)](https://agentmods.dev/skills/gsd-build/agent-inbox/skill)
Your own site
<a href="https://agentmods.dev/skills/gsd-build/agent-inbox/skill"><img src="https://agentmods.dev/badge/skills/gsd-build/agent-inbox/skill.svg" alt="Measured on agentmods" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 846 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 $0.00054 $0.00846
Opus 5 $0.00027 $0.00423
Sonnet 5 $0.00011 $0.00169
Haiku 4.5 $0.00005 $0.00085

Measured 5d ago against content hash d93b71ad1776, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

agent-inbox 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 5d 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.

skill/SKILL.md · 71 lines

What it actually says

<when_to_use>

  • Testing sign-up / auth flows that require email verification
  • Receiving "confirm your account" or "verify your email" links
  • Any automated workflow where you need to receive an email
  • E2E testing of email-sending features </when_to_use>
  • mcp__agent-inbox__create_inbox — Create a new temporary inbox. Optional name parameter for easy reference.
  • mcp__agent-inbox__check_inbox — Check for messages. Returns subjects, bodies, and extracted confirmation links.
  • mcp__agent-inbox__wait_for_email — Poll until a matching email arrives. Filters by from and subject_contains. Auto-retries with backoff.
  • mcp__agent-inbox__verify_email — One-shot: polls for confirmation email, extracts link, visits it via HTTP GET. Three steps in one call.
  • mcp__agent-inbox__list_inboxes — List all active inboxes in this session.
  • mcp__agent-inbox__delete_inbox — Delete an inbox when done.

Fast path (recommended) — use verify_email for the common case:

  1. Create inboxcreate_inbox({ prefix: "signup", name: "test" })
  2. Use the address — Enter it in a sign-up form, invite field, etc.
  3. Verify in one callverify_email({ address: "test", subject_contains: "confirm" }) — polls for the email, extracts the link, visits it via HTTP.
  4. Clean updelete_inbox({ address: "test" })

Manual path — when you need more control:

  1. Create inboxcreate_inbox({ prefix: "signup", name: "test" })
  2. Use the address — Enter it wherever the service asks for an email.
  3. Wait for emailwait_for_email({ address: "test", from: "[email protected]", timeout_seconds: 60 }) — polls with backoff until a matching email arrives.
  4. Act on links — Navigate to the confirmation link via browser automation or HTTP.
  5. Clean updelete_inbox({ address: "test" })

<important_notes>

  • Named inboxes: pass name to create_inbox, then use that name in all other tools instead of the full email address.
  • Fallback providers: mail.tm is primary, 1secmail kicks in automatically if mail.tm is down.
  • Inboxes are cleaned up automatically when the MCP server shuts down.
  • Some services block disposable email domains. If sign-up is rejected, the service may have these domains on a blocklist. </important_notes>
1. create_inbox(prefix: "auth-test", name: "signup")
   → [email protected] (name: signup)

2. Fill sign-up form with that address + a password

3. verify_email(address: "signup", subject_contains: "confirm")
   → Email verified successfully!
     HTTP Status: 200
     Final URL: https://myapp.com/welcome

4. delete_inbox(address: "signup")
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. 5d ago First seen · 71 lines · 54 tokens per session scan A d93b71ad1776

Subscribe to this mod's changes

agent-inbox is a skill published in the GitHub repository gsd-build/agent-inbox (61 stars, last pushed 4mo ago), licensed MIT. It adds 54 tokens to every session and 846 once invoked, about $0.0003 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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