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

Goes well past the annotations by disclosing the exact field-by-field return shape, the upstream source (SEC EDGAR Form 4), and — critically — the per-call cost of 0.01 USDC via x402 with the accepted chains. Pricing and payment rail are behavioral facts an agent cannot get from readOnly/idempotent hints, so this adds real value.

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 tight sentences: trigger, return shape, source and cost. The most decision-relevant facts — what it does and what it costs — are front-loaded with 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?

Despite an output schema existing (so return values needn't be enumerated), the description summarizes them anyway and adds the sourcing and payment context that structured fields omit. Only minor gap: no guidance on rate/payment failure behavior or what happens for tickers with no insider activity.

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 100% and both parameters (ticker, days 1-180 with default 30) are documented in the schema itself. The description's phrase 'recent ... filings' and 'for the window' loosely gestures at the look-back period but adds no format, default, or bounds detail beyond the schema. Baseline 3 applies.

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 and resource ('what a company's insiders bought and sold') and immediately follows with the data shape ('one row per transaction from the company's recent SEC Form 4 filings'). The Form 4 / EDGAR framing cleanly separates it from sibling filing tools like get_sec_8k and get_sec_filings.

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?

Opens with an explicit trigger condition ('Use when an agent needs what a company's insiders bought and sold'), which gives a clear selection rule. It does not name an alternative or state when NOT to use it — e.g. it never routes the agent to get_sec_filings for raw filings versus parsed trades — so a bit of inference is left.

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