coincap_rates

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered structurally. The description adds only the upstream source (CoinCap); it says nothing about base currency, freshness/caching, or that all rates are returned unfiltered, which are the traits an agent would want here.

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?

A single short sentence with the resource front-loaded and zero filler. It is efficient but borders on under-specification rather than being tight-but-complete.

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?

With zero params, no output schema and solid annotations, the needs are modest, but the description never states what a caller actually gets back (base currency, which fiat/crypto pairs, snapshot vs live). An agent knows the topic but not the shape of the result.

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 there is nothing for the description to disambiguate and the baseline applies. It could have clarified that calling it returns the full rate set with no filtering, but no parameter coverage gap exists.

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 gives a specific verb (List) and resource (crypto and fiat exchange rates) plus the data source (CoinCap). It distinguishes itself reasonably from sibling coincap_assets/coincap_asset_detail by focusing on rates rather than asset metadata, though it doesn't explicitly call out that contrast.

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?

There is no guidance on when to pick this over the many other rate tools in the catalog (frankfurter_latest, exchangerate_latest, currency_api_rates, coinlore_tickers, forex_latest). No prerequisites, no exclusions, no alternative named.

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