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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false. The description adds 'Read-only' and 'No API key required' but does not disclose additional behavioral traits beyond the annotations. The description does not contradict annotations.

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?

The description is a compact three-sentence paragraph. Every sentence adds unique value: the first defines the action, the second provides usage examples and alternatives, and the third clarifies parameters and access. No redundant or unnecessary text.

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?

Given the tool's simplicity (top cryptocurrencies list), the description covers purpose, data fields (prices, market caps, 24h changes), ranking basis (market cap), usage examples, alternative tool, and access requirement (no API key). The lack of an output schema is acceptable as the return structure is implied by the described data fields.

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 input schema has low description coverage (33%): only rationale has a schema description. The tool description adds meaning for limit ('caps results') and quotes ('sets the quote currencies (default USD)'), compensating for missing schema descriptions. However, it doesn't mention the required rationale parameter, which is already described in schema.

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 clearly states the tool retrieves current prices, market caps, and 24h changes for top cryptocurrencies ranked by market cap. It distinguishes itself from sibling getTickersById by specifying that getTickers is for top coins or market snapshots.

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 says 'Use for 'top 5 coins', 'top crypto today', 'biggest cryptocurrencies', or a market snapshot' and 'For one specific coin use getTickersById'. Also notes 'No API key required', providing clear when-to-use and alternatives.

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