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

With no annotations, the description must carry the load, and it does disclose several real traits: a paid/PRO tier requirement, a hard cap of 15 companies, and that results are aggregated (net buy/sell) rather than raw transactions. It omits error behavior for unknown tickers, how the 15-item limit is enforced, and whether partial day ranges are honored.

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?

One compact sentence, front-loaded with the tier marker and the resource, followed by the constraints. 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 3-parameter tool with no output schema and no annotations, the core semantics are present, but the absence of guidance on how the summary is shaped (per company? combined?) and on failure modes for invalid tickers leaves meaningful gaps.

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 only 33% (only access_token is documented in the schema), so the description has to compensate, and it does: it pins down that companies accepts names or tickers and caps at 15, and that days defines the lookback window. The access_token flow is already covered by the schema. This is meaningfully beyond the schema, though it doesn't state a default for days.

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 names a specific verb-implied resource: insider activity across a set of companies, aggregated into net buy/sell value. It conveys scope (up to 15 companies, N days) that makes it feel distinct from a raw trade feed, but it never names buy_scanner or insider_trades, so it does not actively differentiate from siblings.

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?

"PRO." hints at a paid/subscriber gate but there is no when-to-use guidance, no mention of the alternative sibling tools, and no stated prerequisites beyond the implicit auth. An agent has to guess whether this or insider_trades is the right call.

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