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

With no annotations, the description carries the behavioral disclosure burden. It does disclose that the result is a 'signed movers:v0 snapshot' and that ordering is by delta z-score, which is useful. However, it does not mention whether the data is live or cached, what the return shape looks like, or any rate/access constraints, though as a read-only getter the risk is modest.

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?

Single sentence, front-loaded with the key concept, and contains no filler. 'Today's biggest movers across the archive' immediately conveys scope, while the parenthetical adds precision about the snapshot and ranking metric without bloating the definition.

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 parameterless tool, the description is sufficient to know what the tool conceptually returns and how it is ordered. However, since there is no output schema, the description does not fully specify the returned item structure, so an agent cannot precisely anticipate field names or types. This is a clear gap, but not a severe one for such a simple tool.

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 input schema has zero parameters, so there is nothing for the description to add about parameter meaning. The baseline for a parameterless tool is 4, and the description enriches context by explaining the snapshot and ranking criteria, which is more than the schema alone provides.

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 identifies the resource ('today's biggest movers across the archive') and the key aspect of the data ('ranked by delta z-score'). It lacks an explicit verb like 'list' or 'get,' but the tool name and phrasing make the purpose obvious. It does not explicitly distinguish itself from get_datum or get_panel, though the movers snapshot concept is sufficiently unique.

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 implies this tool is for retrieving today's movers, but it gives no explicit guidance about when to choose it over siblings such as search_series or get_datum. There are no stated conditions, exclusions, or alternatives, leaving the agent to infer usage from the name and phrasing alone.

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