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

With no annotations, the description bears the full behavioral burden; it does disclose what each listed row carries (current-quarter GDP nowcast as % q/q SAAR, plus share of world GDP), which signals a read-only enumerating operation. It says nothing about ordering, completeness of the economy universe, or pagination, which are the traits an agent would still want.

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

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

One front-loaded sentence with the resource first and the returned metrics second; no filler or hedging. Nothing could be removed without losing information.

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

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

No output schema exists, so the description must convey the return shape; it names two of the fields but not the identity fields (economy names/codes) or the structure of the aggregates. Adequate but thin for a listing endpoint whose return payload defines its usefulness.

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

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

The tool takes zero parameters, so the schema carries no parameter meaning to add to; baseline 4 applies. The description correctly implies no filtering is possible.

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

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

States a specific verb ('List') and resource ('modelled economies and aggregates') and even names the returned metrics (nowcast, share of world GDP). It does not, however, draw a boundary against siblings get_aggregate and get_nowcast, which clearly overlap in subject matter.

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

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

No guidance on when to prefer this directory-style call over get_nowcast or get_aggregate, and no prerequisites or exclusions are stated. The agent must infer usage from the name alone.

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