comp-package

A comparable-sales report for one property, delivered as an Excel workbook. Comparable sales, or comps, are nearby properties used to estimate what a subject property may be worth.

In plain words
What is it for?
Use it to pull Zillow data, estimate after-repair value (ARV), model four renovation scenarios, calculate a maximum allowable offer, and identify potential buyers.
Why use it?
It filters sales and active listings to a real boundary and accounts for property condition, reducing the risk of using irrelevant comparisons. It also lays out repair and offer calculations in one file.

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/datasift-ty-personal/siftstack/comp-package
Any agent
npx skills add DataSift-Ty-Personal/SiftStack --skill comp-package
Clone the repo
git clone --depth 1 https://github.com/DataSift-Ty-Personal/SiftStack

Made for: Claude Code, Codex.

Per session 143 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,403 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 $0.00143 $0.01403
Opus 5 $0.00072 $0.00701
Sonnet 5 $0.00029 $0.00281
Haiku 4.5 $0.00014 $0.00140

Measured 2d ago against content hash 11199d71bea9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

comp-package 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 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/zillow_market_pull.py), 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/comp-package/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Comp Package Builder

Build a complete boundary-filtered comp package for a single subject property: sold comps + actives pulled live from the Zillow data API, condition bucketing, a dual-track ARV, 4-tier rehab scenarios, wholesale MAO math, and buyer targeting, delivered as one Excel workbook.

Use this skill when someone says "run comps on this property", "what's the ARV", "build a comp package", or shares a map with a drawn boundary and an address.

Requirements

  • Python 3.10+ with requests and openpyxl
  • An OpenWeb Ninja "Real-Time Zillow Data" API key in the OPENWEBNINJA_API_KEY environment variable (free tier available at openwebninja.com)

Workflow

Step 1: Establish subject truth from the county, not aggregators

Pull the county assessor card first (beds, baths, living sqft, year built, condition grade, sale history). Aggregator sites routinely report the wrong bedroom count (a Knox County card said 2/1 where aggregators said 5 bed). The county card also reveals the seller story: forced-sale deed types (Master's deed = tax sale, Trustee's deed = foreclosure), purchase price, and current tax delinquency are your negotiation leverage.

Step 2: Map the drawn boundary

Convert the user's drawn boundary into two machine filters:

  1. A lat/lon bounding box (read corner coordinates off the map's landmarks)
  2. A street-name whitelist regex (every street visibly inside the loop)

Apply BOTH: the bbox catches street-name misses, the street list catches bbox bleed across a highway or interstate edge. When a comp sits near the line, verify it against the map before keeping it.

Step 3: Pull sold + active comps via the API

Run scripts/zillow_market_pull.py (see references/api_contract.md for the endpoint contract and its traps). Key trap: a single sold search returns at most 41 rows (about 5 weeks in an active zip), so the script partitions by min_price/max_price bands and recursively splits any saturated band. Pull 12-24 months.

The API only sees MLS activity. Auction, wholesale, and off-market transfers will NOT appear; pull those from county records when they matter.

Read the full file on GitHub · 85 lines

Files

What ships with it

4 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. 2d ago First seen · 85 lines · 143 tokens per session scan A 11199d71bea9

Subscribe to this mod's changes

comp-package is a skill published in the GitHub repository DataSift-Ty-Personal/SiftStack (21 stars, last pushed 4d ago), licensed MIT. It adds 143 tokens to every session and 1,403 once invoked, about $0.0007 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 skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

chat-pet-sprite-creation

Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.

microsoft/vscode · 53 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens

babysit-pr

Babysit a GitHub pull request after creation by continuously polling review comments, CI checks/workflow runs, and mergeability state until the PR is merged/closed or user help is required. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and keep…

openai/codex · 114 tokens

imagegen

Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output…

openai/codex · 113 tokens

agent-host-chat-contributions

Build and review cross-cutting agent-host chat behavior through lifecycle contributions. Use when adding turn lifecycle side effects, prompt or context injection, restored-history transformation, protocol-action observation, or when reviewing changes that add code to AgentSideEffects or AgentService.

microsoft/vscode · 56 tokens