mcp-fantastical: Instructions file for Codex

AGENTS.md

mcp-fantastical AGENTS.md is an instructions file for Codex, OpenCode from aplaceforallmystuff/mcp-fantastical. It costs 303 tokens per session, scanned A, original, MIT.

Repository guidance for an MCP server that lets AI tools create events in and query the Fantastical calendar app on macOS.

In plain words
What is it for?
Use it when developing, testing, or publishing Fantastical calendar tools that use its URL scheme and AppleScript.
Why use it?
It explains the project structure, local integration methods, platform requirements, and publishing checks needed to work safely in the codebase.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: mentions AGENTS.md.

This is aplaceforallmystuff/mcp-fantastical's own configuration. It tells Codex and OpenCode how to work on mcp-fantastical itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcp-fantastical configures →

Reuse

Borrowing it

Nothing to install: this file belongs to aplaceforallmystuff/mcp-fantastical. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/aplaceforallmystuff/mcp-fantastical/main/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/aplaceforallmystuff/mcp-fantastical

Made for: Codex, OpenCode.

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 mcp-fantastical AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/aplaceforallmystuff/mcp-fantastical/agents-md/github.svg)](https://agentmods.dev/instructions/aplaceforallmystuff/mcp-fantastical/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/aplaceforallmystuff/mcp-fantastical/agents-md"><img src="https://agentmods.dev/badge/instructions/aplaceforallmystuff/mcp-fantastical/agents-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for mcp-fantastical AGENTS.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/aplaceforallmystuff/mcp-fantastical/agents-md"><img src="https://agentmods.dev/badge/instructions/aplaceforallmystuff/mcp-fantastical/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 303 This file is loaded in full into every session.
When invoked 303 The same file — it is already loaded in full.
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 $0.00303 $0.00303
Opus 5 $0.00151 $0.00151
Sonnet 5 $0.00061 $0.00061
Haiku 4.5 $0.00030 $0.00030

Measured 9d ago against content hash e4f68cf85b37, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

mcp-fantastical AGENTS.md 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 9d 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.

AGENTS.md · 42 lines

What it actually says

AGENTS.md - mcp-fantastical

MCP server for Fantastical calendar app - create events and manage schedules.

Tech Stack

  • Language: TypeScript
  • Runtime: Node.js (ES modules)
  • Protocol: Model Context Protocol (MCP)

Architecture

src/
├── index.ts          # Server entry, tool registration
└── tools/
    ├── events.ts     # Event creation via URL scheme
    └── calendar.ts   # Calendar queries via AppleScript

Integration Method

Uses Fantastical's URL scheme (x-fantastical3://) for event creation and AppleScript for calendar queries. No API key needed - works with local Fantastical installation.

Development

npm run build    # Compile TypeScript
npm run watch    # Watch mode

Constraints

rules:
  - id: macos-only
    description: Requires macOS with Fantastical installed
  - id: url-encoding
    description: Event details must be URL-encoded
  - id: natural-language
    description: Fantastical parses natural language dates

Pre-Publish

Run /publish-mcp before any npm publish — mandatory pipeline that handles tests, secret scan, sanitize, docs check, version bump, tag, push, and publish in strict order. Do not run npm publish directly.

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. 9d ago First seen · 42 lines · 303 tokens per session scan A e4f68cf85b37

Subscribe to this mod's changes

mcp-fantastical AGENTS.md is an instructions file published in the GitHub repository aplaceforallmystuff/mcp-fantastical (17 stars, last pushed 27d ago), licensed MIT. It adds 303 tokens to every session, about $0.0015 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.

Related

Other instructions, from other repositories

next.js AGENTS.md

AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.

vercel/next.js · 7,296 tokens

codex AGENTS.md

AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.

openai/codex · 5,153 tokens

vscode buildNext.instructions.md

Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).

microsoft/vscode · 6,785 tokens

vscode oss-third-party-notices.instructions.md

Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).

microsoft/vscode · 5,001 tokens

langchain AGENTS.md

AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.

langchain-ai/langchain · 4,469 tokens

deepseek-harness AGENTS.md

AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.

deepseek-ai/deepseek-harness · 3,735 tokens