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

Annotations already cover read-only/idempotent/non-destructive safety, so the description correctly focuses on substance: it discloses that results are joined with insider activity, include time-of-day (before open / after close) and a countdown, and that buying is limited to open-market purchases in the look-back window. Pagination and the effect of the limit cap are not mentioned, which keeps it at 4.

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?

Three sentences, front-loaded with the core behavior, then the flag's payoff and the tickers variant. The 'rare and closely watched signal' clause justifies the flag's importance rather than repeating mechanics, so only minor trimming is possible.

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 rich annotations, an output schema, and 80% parameter coverage, the remaining burden on the description is small and it meets it; only the limit/result-cap behavior is unaddressed, which is minor given the output schema.

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 80%, so the baseline is 3, but the description adds real semantic meaning: it explains what only_with_insider_buying=true selects and shows the tickers pattern for the single-company case. days_ahead and insider_lookback_days are left entirely to the 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?

States a specific verb+resource (companies reporting earnings soon) and the enrichment performed (joined with recent insider activity, date/time, countdown). The insider-join framing also separates it from pure insider tools like find_insider_buying, so an agent can tell what it uniquely returns.

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?

Gives two concrete usage contexts: the only_with_insider_buying=true case ('which companies reporting soon have insiders been buying?') and the 'when does X report?' case with the exact parameter values to pass. It does not name sibling alternatives or state exclusions, so it stops short of a 5.

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