agentmailbox

agentmailbox is a skill for Claude Code, Codex from RagavRida/agentsmcp. It costs 75 tokens per session (2,326 once invoked), scanned A, original, MIT.

A persistent context and messaging system for coding agents, with threads that continue across sessions, tools, and supported platforms.

In plain words
What is it for?
Use it to recover previous work, exchange messages with other agents, preserve decisions, and carry context between coding environments.
Why use it?
It helps an agent resume work with earlier context instead of starting from scratch.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; mentions Claude Code; mentions Gemini CLI.

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/ragavrida/agentsmcp/antigravity
Any agent
npx skills add RagavRida/agentsmcp --skill antigravity
Clone the repo
git clone --depth 1 https://github.com/RagavRida/agentsmcp

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 agentmailbox

README.md
[![agentmods](https://agentmods.dev/badge/skills/ragavrida/agentsmcp/antigravity.svg)](https://agentmods.dev/skills/ragavrida/agentsmcp/antigravity)
Your own site
<a href="https://agentmods.dev/skills/ragavrida/agentsmcp/antigravity"><img src="https://agentmods.dev/badge/skills/ragavrida/agentsmcp/antigravity.svg" alt="Measured on agentmods" height="20"></a>
Per session 75 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,326 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 5.1 $0.00075 $0.02326
Opus 5 $0.00037 $0.01163
Sonnet 5 $0.00015 $0.00465
Haiku 4.5 $0.00007 $0.00233

Measured 6d ago against content hash d8aec4414704, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

agentmailbox 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 6d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/setup.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/antigravity/SKILL.md · 267 lines

How it starts

The opening of the file, as written. The whole thing — 267 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AgentMailbox — Context Sync for AI Agents

Every agent has a mailbox. No agent ever starts cold.

AgentMailbox is a context-sync protocol that gives you durable, persistent threads across sessions, tools, and restarts. When you receive a message, you get the full thread state — snapshot, structured summary, recent messages — so you can pick up exactly where the last agent (or the last session) left off.

When to Use This Skill

  • Session start: Check your mailbox for context from previous sessions
  • "What was I working on?": Receive and sync threads to restore context
  • Multi-agent tasks: Send messages to other agents, coordinate via threads
  • Before switching tools: Send a summary so the next tool picks up seamlessly
  • After completing work: Record decisions, artifacts, and progress to the thread
  • Cross-platform continuity: Context follows the user across Cursor, Claude Desktop, Antigravity, Continue, and any MCP client

RULE #1: Memory First — ALWAYS

When a user gives you ANY query or task:

  1. IMMEDIATELY call agentsmcp_context_briefing with the user's query as the task parameter
  2. Read the returned briefing — it contains relevant files, symbols, decisions, tasks, and relationships from persistent memory
  3. If the briefing returns results, USE THEM as your starting context instead of reading raw files
  4. Only fall back to grep / view_file / read_file when the briefing returns empty results

Context Lookup Priority (use in order)

  1. agentsmcp_context_briefing — one-shot task briefing (graph + index combined)
  2. agentsmcp_get_index — look up a specific file/symbol by key (~200 tokens vs full file)
  3. agentsmcp_search_index — keyword search across all indexed entries (replaces grep)
  4. agentsmcp_query_graph — relationship traversal (find connected files/symbols/decisions)
  5. LAST RESORT: grep / view_file — only when memory has no entry

Setup

Quick Setup (MCP)

AgentMailbox works via MCP. Add this to your MCP configuration:

Read the full file on GitHub · 267 lines

Files

What ships with it

2 files 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. 6d ago First seen · 267 lines · 75 tokens per session scan A d8aec4414704

Subscribe to this mod's changes

agentmailbox is a skill published in the GitHub repository RagavRida/agentsmcp (1 stars, last pushed 1mo ago), licensed MIT. It adds 75 tokens to every session and 2,326 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.