Geo-Parity

Statutory corporate and top income-tax rates by country

compare_tax_rates

Read-onlyIdempotent

Statutory tax schedules from the OECD, compared or ranked. Given countries (two or more ISO alpha-2 codes), returns side by side the corporate income-tax rate (combined central plus average sub-national, central only, and a small-business rate where one exists; OECD Corporate Tax Statistics, all 41 spine countries) and, for OECD members, the top personal income-tax rate with the earnings threshold at which it starts as a multiple of the average wage, plus the marginal rate with employee social contributions at that point (OECD Tax Database, 26 of the spine). Without countries, ranks the spine by one metric. A country OECD's PIT flow does not cover has no personal block and is dropped from a PIT ranking, never scored 0. Rates are statutory, not effective: incentives, surtaxes and special regimes are outside the data, and this does not replace the blended take-home profiles behind compare_contract. Statutory figures for information only — not legal or tax advice; every response says so first.

Input Schema

Name	Required	Description	Default
`sort`	No	Ranking direction. Ignored when `countries` is given.	highest
`limit`	No	Return at most this many countries in a ranking.
`metric`	No	Ranking metric. Ignored when `countries` is given.	corporateCombined
`countries`	No	Comma-separated ISO alpha-2 codes, two or more (e.g. "DE,IE,TH"). Omit to get a ranking instead.

Output Schema

Name	Required	Description	Default
`ok`	No
`rows`	No
`metric`	No
`caveats`	No
`attribution`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 1, 2026
- addedInput schema / examples
```
Added value: +[
+  {
+    "countries": "DE,IE,TH"
+  }
+]
```
AddedSep 5, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations already mark this read-only/idempotent, and the description goes well beyond them: it discloses that OECD-uncovered countries have no `personal` block, are dropped from PIT rankings and are never scored 0, that figures are statutory not effective, and that a disclaimer is prepended to every response.

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

Conciseness4/5

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

A single dense paragraph that leads with the core purpose and then layers scope, fallbacks and caveats. Nearly every clause carries information, though the closing disclaimer sentence is somewhat expendable for tool-selection purposes.

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

Completeness5/5

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

For a read-only multi-metric comparison tool with a full schema and an output schema, the description covers the invocation branch, the data limits, edge-case country handling and caveats. An agent has everything needed to call it correctly.

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

Parameters4/5

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

Schema coverage is 100%, so the baseline is 3, but the description adds real meaning: it expands what the `metric` options actually measure (combined vs. central vs. small-business corporate rate; PIT top, threshold as a multiple of average wage, marginal rate including employee social contributions) and clarifies `sort`/`metric` are ignored when `countries` is given.

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

Purpose5/5

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

States a specific verb and resource — statutory corporate and top personal income-tax rates compared or ranked by country — and names the source datasets and country scope. An agent can tell it apart from compare_effective_tax and compare_tax_burden without opening a schema.

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

Usage Guidelines5/5

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

Explicitly branches on the presence of `countries` (side-by-side comparison vs. ranking) and routes the agent away from alternatives by stating this is not the effective/blended take-home data behind `compare_contract`. It also names the exclusion cases (non-OECD-PIT countries).

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

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