What is calendar-mcp CLAUDE.md?

Development instructions for a Deno monorepo containing two related TypeScript packages for reading macOS Calendar data. A monorepo is one repository that holds multiple packages or projects.

It helps develop the calendar library and its MCP server, including read-only access to the macOS Calendar database. It also documents publishing to JSR.

It gives contributors the commands and project structure needed to format, lint, type-check, run, and publish the packages consistently.

How wyattjoh/calendar-mcp configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to wyattjoh/calendar-mcp. 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/wyattjoh/calendar-mcp/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/wyattjoh/calendar-mcp

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/wyattjoh/calendar-mcp/claude-md/github.svg)](https://agentmods.dev/instructions/wyattjoh/calendar-mcp/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/wyattjoh/calendar-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/wyattjoh/calendar-mcp/claude-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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/wyattjoh/calendar-mcp/claude-md"><img src="https://agentmods.dev/badge/instructions/wyattjoh/calendar-mcp/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 567 This file is loaded in full into every session.

When invoked 567 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.

Model	Per session	Once invoked
Fable 5.1	$0.00567	$0.00567
Opus 5.5	$0.00227	$0.00227
Sonnet 5.5	$0.00113	$0.00113
Haiku 4.5	$0.00057	$0.00057

Measured 2mo ago against content hash 15123593e92f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

calendar-mcp CLAUDE.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 2mo 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.

CLAUDE.md · 73 lines

How it starts

The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Commands

Development Commands

deno task fmt - Format all code with Deno formatter
deno task lint - Run Deno linter on all code
deno task check - Type check all TypeScript code

Package-specific Commands (in packages/calendar-mcp/)

deno task dev - Run the MCP server in development mode (requires macOS for Calendar access)
deno task start - Run the MCP server

Publishing

deno publish - Publish packages to JSR (requires proper permissions)

Architecture

This is a Deno monorepo with two packages:

packages/calendar/

Core calendar library that provides direct access to macOS Calendar database:

mod.ts: Main export file exposing all public APIs
src/client.ts: Database client with query functions for calendar events
src/types.ts: TypeScript interfaces for calendar events and options
src/utils.ts: Utility functions for formatting events
src/constants.ts: Constants including database path and Core Data epoch

Key features:

Read-only access to macOS Calendar database at ~/Library/Calendars/Calendar.sqlitedb
Functions for retrieving recent, upcoming, and date-range events
Event search and detail retrieval
Support for filtering rescheduled events

packages/calendar-mcp/

Model Context Protocol (MCP) server that exposes calendar functionality:

mod.ts: MCP server implementation with tool registrations
Wraps the calendar library functions as MCP tools
Provides 6 tools: get-recent-events, get-upcoming-events, get-events-by-date-range, search-events, get-todays-events, get-event-details
Uses stdio transport for MCP communication

Dependencies

@db/sqlite: SQLite database access for reading Calendar.sqlitedb
@modelcontextprotocol/sdk: MCP SDK for server implementation
zod: Schema validation for MCP tool inputs

Database Schema

The code queries the macOS Calendar SQLite database with these key tables:

Read the full file on GitHub · 73 lines

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.

2mo ago First seen · 73 lines · 567 tokens per session scan A 15123593e92f

Subscribe to this mod's changes

calendar-mcp CLAUDE.md is an instructions file published in the GitHub repository wyattjoh/calendar-mcp (2 stars, last pushed 1y ago), licensed MIT. It adds 567 tokens to every session, about $0.0023 per session on Opus 5.5. 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.

calendar-mcp CLAUDE.md next to 6 instructions from other repositories
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calendar-mcp CLAUDE.mdwyattjoh/calendar-mcp	Instructions file	2	1y ago	MIT	A	567	Claude Code
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vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

calendar-mcp: Instructions file for Claude Code