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

The readOnlyHint annotation already covers safety, and the description adds the temporal 'currently' scope plus that a list is returned. It does not explain what 'trending' means, the ranking basis, or additional behavior, but for a read-only, zero-parameter tool this is a reasonable baseline.

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 single sentence that is front-loaded with the verb and resource, containing no filler or repetition. It is appropriately sized for a zero-parameter, read-only tool.

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 tool, the description adequately conveys that the output is a list of currently trending cryptocurrencies. Without an output schema, it could go further by defining 'trending' criteria, but the missing detail is minor given the tool's simplicity.

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, so there is no schema ambiguity for the description to clarify. The baseline for parameterless tools is 4 because no additional meaning is needed.

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 uses a specific verb and resource: 'Lists the currently trending cryptocurrencies.' It clearly states what the tool does, but it does not explicitly distinguish it from siblings like market_top_movers or market_coins, which could overlap conceptually.

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?

The phrase 'currently trending' implies this is the tool to use when a user asks about trending cryptocurrencies. However, no explicit when-not-to-use guidance or alternative routing is provided, leaving the agent to infer boundaries versus similar market tools.

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