top_gainers

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

Annotations already declare readOnlyHint and destructiveHint. The description adds valuable behavioral context: the Bollinger Band analysis methodology, the structured error envelope on failure, and a guarantee of never throwing a raw exception string. This goes beyond the 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 well-organized with an opening sentence followed by Args and Returns sections. It is concise, front-loaded, and every sentence provides useful information without redundancy.

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?

The tool has only 3 parameters, all fully documented in the description. Return values and error behavior are also specified. The description is complete for effective use, even with an output schema present.

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 has no parameter descriptions (0% coverage), but the description compensates fully by documenting each parameter: valid exchange values, valid timeframes, and the limit maximum. This is complete and adds meaning far beyond the raw 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's function: 'Return top gainers for an exchange and timeframe using Bollinger Band analysis.' This specifies a concrete verb, resource, and methodology, distinguishing it from sibling tools like top_losers.

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 purpose implies when to use (screening top gainers), but there is no explicit guidance on when not to use it or which alternative might be better suited. With many sibling screener tools, explicit differentiation would strengthen this dimension.

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