infracost_mcp: Instructions file for Claude Code

CLAUDE.md

infracost_mcp CLAUDE.md is an instructions file for Claude Code from phildougherty/infracost_mcp. It costs 1,161 tokens per session, scanned A, original, MIT.

A set of project instructions for an MCP server, a program that lets coding assistants use external tools, to estimate and manage the cost of Terraform infrastructure.

In plain words
What is it for?
Use it when developing, building, running, or testing this Infracost MCP server.
Why use it?
It gives the coding assistant the project’s build commands, configuration requirements, architecture, and testing procedure.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: reads .claude/ paths; mentions CLAUDE.md; positional $N argument.

This is phildougherty/infracost_mcp's own configuration. It tells Claude Code how to work on infracost_mcp 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 infracost_mcp configures →

Reuse

Borrowing it

Nothing to install: this file belongs to phildougherty/infracost_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/phildougherty/infracost_mcp/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/phildougherty/infracost_mcp

Made for: Claude Code.

Wrote this? Show the measurements

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Per session 1,161 This file is loaded in full into every session.
When invoked 1,161 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 $0.01161 $0.01161
Opus 5 $0.00580 $0.00580
Sonnet 5 $0.00232 $0.00232
Haiku 4.5 $0.00116 $0.00116

Measured 9d ago against content hash 758fca15d50e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

infracost_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 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.

CLAUDE.md · 135 lines

How it starts

The opening of the file, as written. The whole thing — 135 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.

Project Overview

This is an MCP (Model Context Protocol) server that provides Infracost tools to Claude Desktop and Claude Code. It enables cost estimation and governance for Terraform infrastructure through both CLI commands and the Infracost Cloud API.

Build and Development

# Install dependencies
npm install

# Build TypeScript to JavaScript
npm run build

# Watch mode for development
npm watch

# Start the server (requires build first)
npm start

The build output goes to dist/ and must exist before running the server.

Testing the MCP Server

Since this is an MCP server project with no test suite, testing is done by running the server:

# Build first
npm run build

# Test with environment variables
INFRACOST_SERVICE_TOKEN=ics_v1_... INFRACOST_ORG=your-org node dist/index.js

The server runs on stdio and will log configuration on startup. Use .mcp.json for Claude Code integration.

Architecture

Entry Point and MCP Server (src/index.ts)

  • Initializes MCP server using @modelcontextprotocol/sdk
  • Loads .env for INFRACOST_SERVICE_TOKEN and INFRACOST_ORG
  • Registers 16 tools exposed to Claude
  • Exposes 4 MCP resources for Infracost usage YAML files
  • Routes tool requests to InfracostTools class methods
  • All tool calls validate input via Zod schemas

Tool Implementation (src/tools.ts)

The InfracostTools class handles all tool implementations:

  • CLI-based tools: Delegate to src/cli.ts functions (breakdown, diff, output, upload, comment)
  • API-based tools: Delegate to InfracostCloudAPIClient from src/api.ts
  • Each handler validates args with Zod, executes operation, and returns MCP-formatted response
  • All API operations require INFRACOST_SERVICE_TOKEN and org slug

CLI Wrapper (src/cli.ts)

Wraps the infracost CLI tool:

  • Uses execFileAsync for safe command execution
  • All file paths are resolved to absolute paths
  • Supports JSON parsing for structured output
  • checkInfracostInstalled() verifies CLI availability

Read the full file on GitHub · 135 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.

  1. 9d ago First seen · 135 lines · 1,161 tokens per session scan A 758fca15d50e

Subscribe to this mod's changes

infracost_mcp CLAUDE.md is an instructions file published in the GitHub repository phildougherty/infracost_mcp (2 stars, last pushed 10mo ago), licensed MIT. It adds 1,161 tokens to every session, about $0.0058 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.

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