Most active stocks

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description earns credit by adding behavior beyond the annotations: that values are cumulative for the current trading day and that as_of reflects the screener's last update, which tells the agent how fresh the data is.

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?

A single front-loaded sentence that leads with what is returned and where. Both clauses carry information (ranking basis, freshness semantics) and there is no filler.

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 two-optional-parameter screener with no nested objects and no output schema, the description covers ranking basis, universe (US stocks), timeframe, and freshness. It is close to complete; the absence of any hint about result shape or result count is a minor gap given there is no output schema to fall back on.

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 100%, so the schema already documents both 'by' (with enum) and 'top'. The description's 'ranked by share volume or trade count' restates the 'by' semantics and adds nothing for 'top', matching the baseline 3 when the schema does the heavy lifting.

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 resource and scope: 'Today's most active US stocks ranked by share volume or trade count,' which is far more precise than the bare title. It does not, however, explicitly distinguish itself from the close sibling market_movers, leaving the agent to infer the difference (ranking by activity vs. price change).

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 ranking criteria implicitly signal the query this tool answers, so a competent agent can infer usage. But there is no explicit when-to-use vs. the analogous market_movers or market_quotes tools, and no stated exclusions or prerequisites.

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