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

The description openly discloses that it is a free public scan with no API key required, reinforcing the readOnlyHint and openWorldHint annotations. It mentions data refresh frequency (~60s tick) and the fields returned, giving users a clear expectation of behavior and output.

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 concise yet informative, with each sentence contributing valuable information: function, usage, output fields, refresh rate, and a caution about symbol collisions. No redundancy or irrelevant details are present, and the structure flows logically from discovery to deeper analysis.

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 as a read-only scan, the description is complete. It covers purpose, usage, return fields, refresh behavior, and a specific caveat. It sets expectations for integration with other tools, making it sufficient for a user to understand the tool's role and limitations.

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 schema already provides clear descriptions for both parameters (limit with range and default, direction with enum and default). The description does not add extra semantic meaning beyond the schema, but it also does not contradict or omit critical details. Since the schema is comprehensive, a score of 4 is appropriate.

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 explicitly states the tool's function: scanning the crypto universe for top 24h movers, either gainers or losers, sorted by change percent. It also distinguishes this tool from related tools (get_candles, get_market_context) by positioning it as a discovery step, making its purpose clear and specific.

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 description provides clear usage guidance: use it to discover candidates beyond the watchlist, then follow up with get_candles and get_market_context. It also advises passing coinId directly and warns against re-resolving by symbol, giving practical 'when-to-use' and 'how-to-use' instructions.

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