The Johns Islander — Kiawah, Seabrook and Johns Island

What it costs to buy and own

true_cost

Read-onlyIdempotent

The site's true-cost calculator: for a price on Kiawah, Seabrook or Johns Island, the buyer's closing costs, the first year of owning (property tax, association dues, base utilities), what comes later and the seller's side — each line from the fee ledger with how sure it is. An estimate from published fees, not a closing statement or tax advice.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "price": "<price>",
      "place": "<place>"
    },
    "name": "true_cost"
  }
}

Input Schema

Name	Required	Description
`use`	No	primary = the buyer's legal residence (4% assessment); second = second home or rental (6%)
`area`	No	Johns Island only: unincorporated county, inside the City of Charleston, or Kiawah River
`club`	No	Seabrook only: the Seabrook Island Club membership level
`kind`	No
`place`	Yes
`price`	Yes	Purchase price in dollars
`financed`	No

Output Schema

Name	Required	Description
`page`	No	The calculator link with these inputs
`inputs`	No	The inputs as understood
`at_closing`	No	Lines and total
`coming_later`	No	Lines
`not_included`	No	What the estimate leaves out
`sellers_side`	No	Lines
`what_this_is`	No	An estimate from published fees
`first_year_of_owning`	No	Lines and total

Schema Changelog

Changes observed during successful MCP inspections.

First observedOct 19, 2026

TDQS

B3.4/5.0

Behavior4/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine behavioral context beyond that: each line item comes "from the fee ledger with how sure it is" (per-line confidence), and the output is explicitly an estimate, not a closing statement or tax advice. It stops short of 5 because it says nothing about coverage limits of the fee ledger or how uncertainty is expressed.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The purpose is front-loaded in the first clause, which is good, but the description is a single dense run-on that packs the cost breakdown, the ledger-confidence detail, and the disclaimer into one breathless sentence. No sentence is wasted, but the structure could be split for scanability.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With annotations covering safety and an output schema presumably covering the return shape, the description only needs to orient the agent on scope, and it does: it enumerates which cost lines are computed and characterizes the result as an estimate. The remaining gap is parameter-level guidance for the five enum inputs and the conditionality of area/club, which the description leaves entirely to the schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is only 57%, and the description compensates for almost none of it — it names only price and place (the two required params) and says nothing about use, area, club, kind, or financed. The enum params carry their own schema text, but kind and financed are undocumented in both places, so the description fails to close the coverage gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description gives a specific verb+resource ("true-cost calculator") and enumerates the cost categories it computes (buyer's closing costs, first year of ownership, later costs, seller's side), which is clear enough to distinguish it from generic siblings like fees. It never names a sibling or explicitly contrasts with estimate_range, so it falls short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is implied rather than stated: an agent can infer this is for total cost-of-ownership questions about a specific priced property. The only near-guidance is the caveat that it is "an estimate from published fees, not a closing statement or tax advice," which bounds reliability but not tool selection — there is no instruction about when to prefer fees or estimate_range instead.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

All The Johns Islander — Kiawah, Seabrook and Johns Island tools Inspect

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