apibase

OECD Annual GDP and National Accounts

oecd.economy.gdp

Read-onlyIdempotent

Fetch annual GDP and national accounts data for any OECD member country. Returns GDP at current USD exchange rates, gross operating surplus, compensation of employees, and other national accounts aggregates from the OECD National Accounts Main Aggregates database (NAMAIN10). Covers 38 OECD countries from the 1970s to the latest year. Data is sourced from official national statistics offices and harmonised to SNA 2008 standards. Each series includes the exact transaction code (e.g. B1GQ = GDP at market prices), sector, unit of measure (USD millions at exchange rates), and price base. Source: OECD SDMX API, CC BY 4.0, no auth required, unlimited.

Input Schema

TableJSON Schema

Name	Required	Description
`country`	Yes	ISO 3-letter OECD country code (e.g. USA, GBR, DEU, FRA, JPN, CAN, AUS, KOR, ITA, ESP). See OECD reference area codes for the full list of 38 member countries.
`end_period`	No	End year for annual GDP data (e.g. "2024"). Defaults to latest available.
`max_series`	No	Maximum number of time series to return (1–100, default 20). Each series is a unique combination of dimensions such as sector, measure, or adjustment type.
`start_period`	No	Start year for annual GDP data (e.g. "2018"). Defaults to 5 years prior.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`error`	No	Present only when the call failed. Includes error code, message, request_id, and any provider-specific extras.
`result`	No	Tool response payload. Shape varies per tool — consult the tool description and inputSchema. May be an object, array, string, or number depending on the upstream provider response.

Schema Changelog

Changes observed during successful MCP inspections.

First observedSep 22, 2026

TDQS

A4.5/5.0

Behavior5/5

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

Annotations already establish a safe read-only, non-destructive profile, and the description adds substantial behavioral context: data provenance, SNA 2008 harmonisation, inclusion of transaction codes, units in USD millions, CC BY 4.0 licensing, no auth requirement, and unlimited usage. This goes well beyond what the annotations provide.

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

Conciseness5/5

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

The description is front-loaded with the core purpose, then provides efficient, relevant detail about coverage, standards, units, and access. Every sentence adds useful information without bloat.

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?

Given the rich annotations, full schema coverage, and presence of an output schema, the description covers all essential surrounding context: what data is returned, which countries and years are covered, how it is sourced, licensing, authentication, and usage limits. Nothing critical is missing.

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

Parameters3/5

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

Schema description coverage is 100%, so the baseline is 3. The description reinforces 'annual' and country scope but does not add meaningful parameter-level semantics beyond the schema's already detailed parameter descriptions.

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?

The description opens with a specific verb and resource: 'Fetch annual GDP and national accounts data for any OECD member country.' It further distinguishes itself from sibling OECD tools by naming the NAMAIN10 database, the specific aggregates returned, and the 38-country scope.

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

Usage Guidelines4/5

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

The description makes clear that this tool is for annual OECD national accounts data and states the exact country scope, which lets an agent differentiate it from general OECD series tools and country-specific GDP tools. It does not explicitly name alternatives or when-not-to-use conditions, but the context is strong enough to route selection correctly.

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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