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

With no annotations, the description carries the burden and does disclose useful behavior: market-wide scope, last-N-days window, code-P-only filtering, and a value threshold. It omits auth/subscriber requirements (only visible from the access_token schema field), pagination, what max_filings does, and return format, leaving meaningful behavioral gaps.

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 tight sentence that front-loads the core signal (open-market purchases, code P) and qualifies the scope. No filler or redundancy.

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 4-parameter, no-annotation, no-output-schema tool, the description covers purpose and the key filters but leaves max_filings behavior, result shape, and auth requirements unaddressed. Adequate but with clear gaps an agent would want filled.

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 only 25% (just access_token), so the description should compensate more. It does clarify 'days' (last N days) and 'min_value_usd' (value threshold), but max_filings is never explained and access_token semantics come only from 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?

Clear verb (Scan) plus specific resource (Form 4 filings market-wide) and a precise filter (code P open-market purchases above a $ threshold). It is very easy to understand what the tool does, though it never references siblings insider_trades or watchlist to distinguish itself from them.

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 frames the tool as the 'classic insider-buying signal,' which implies a use case (surfacing insider buys), and the 'PRO' marker hints at a paid tier. However, it gives no explicit when-to-use or when-not-to-use guidance and does not say how it differs from insider_trades.

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