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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds minor context (US stocks, current data, ranking) but does not disclose behavior such as pagination limits or that the list is a snapshot. Given the annotations, this is adequate but not rich.

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, tight sentence that leads with the action and resource, lists the categories, and includes the ranking qualifier. There is no redundancy or filler, making it highly concise and well-structured.

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 tool with only two parameters and no output schema, the description covers the core purpose and scope (US stocks, current movers, three categories). It does not describe the return format or any pagination behavior, but given the tool's simplicity and the schema covering parameter constraints, it is largely complete. Minor gaps like limit effect could be added but are not critical.

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 description coverage is 0%, so the description must carry the burden. It does explain the category parameter by enumerating 'gainers, losers, or most active', mapping to the enum. However, the 'limit' parameter is not mentioned, and its default/max are only in the schema. The description partially compensates but leaves the limit behavior undocumented.

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 specific verb 'List' and resource 'current US stock gainers, losers, or most active names', and adds 'ranked by the market-data service' to clarify the output ordering. This distinguishes it from sibling tools like market.history (historical data) and market.quotes (quotes) without ambiguity.

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 no explicit guidance on when to use this tool versus alternatives such as market.history, market.quotes, or market.search. While the purpose is clear, there is no statement of exclusions or conditions for selecting this tool over siblings, leaving the agent to infer usage context.

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