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

Annotations cover the safety profile (readOnly, non-destructive, openWorld), and the description adds useful behavioral detail: success returns list[dict], failures return a structured error envelope with code and retryable, and limit max is 50. It does not mention rate limits or auth, but the added error contract is valuable.

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?

Front-loads the purpose in the first sentence, then uses clear Args and Returns sections. The long exchange list is necessary given zero schema coverage, so no sentence is wasted.

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 annotations covering safety and an output schema present, the description fills the parameter gap and documents error behavior. It omits usage routing relative to sibling screeners, leaving a minor gap for an agent deciding between similar tools.

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?

Schema coverage is 0%, so the description carries the full burden; it lists concrete allowed exchange values, timeframe options, and the limit maximum (50). This compensates completely for the bare schema and goes beyond it.

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?

States a specific verb and resource ('Return top gainers') and scopes it to an exchange and timeframe, with a method (Bollinger Band analysis). It does not explicitly differentiate itself from many sibling scanners like bollinger_scan or volume_breakout_scanner, so it falls short of a 5.

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?

No when-to-use guidance, no prerequisites, and no mention of alternatives such as top_losers or other screeners. The agent must infer usage solely from the tool name.

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