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

Annotations already declare readOnly, idempotent, non-destructive, and open-world behavior, lowering the bar. The description adds meaningful context beyond annotations: it discloses the flat map shape, approximate scale (1,500 exchanges), that it contains only `id` and `name`, and explicitly disclaims market data. With an output schema present, the lack of return-format detail is acceptable.

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?

Two tight sentences with no filler: the first sentence defines the resource and scope, the second routes to dependent tools and the alternative. Every clause earns its place, and key facts are front-loaded.

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?

For a simple, zero-parameter map tool with annotations and output schema already present, the description is complete. It covers what the tool returns, how it relates to downstream required IDs, what it excludes, and which sibling to use instead for richer data. Nothing needed for correct invocation is missing.

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 has zero parameters, and the schema coverage is 100%, so the baseline is 4. The description reinforces this by stating 'It takes no parameters,' which prevents the agent from hunting for required inputs. There is nothing more to add at the parameter level.

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?

The description states a specific verb and resource: it is a 'flat identifier map of roughly 1,500 exchanges as `id` and `name`' and distinguishes itself from siblings by naming what it is not (market data) and what it feeds into. An agent can tell it apart from `get_coingecko_exchanges`, `get_coingecko_exchanges_id`, and `get_coingecko_coins_id_tickers` without opening schemas.

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?

It explicitly tells the agent when to use this tool: to 'resolve a venue name into the `id`' required by two named sibling tools. It also gives an exclusion—'carries no market data'—and points to `get_coingecko_exchanges` for trust scores and volumes. This is clear and actionable routing guidance.

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