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

Annotations already cover safety (readOnly, idempotent, non-destructive), but the description adds behavior they don't: a per-call cost of 0.01 USDC, the x402 payment mechanism, and accepted chains. It also discloses the row-level grain and the aggregate buy/sale totals, which is real behavioral context beyond the annotations.

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?

Two sentences, front-loaded with the use case, then the return shape, then source and cost. Every clause is load-bearing; 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?

With an output schema present, return values need not be explained, yet the description still sketches them; the cost/payment caveat and data source are surfaced. An agent has everything needed to decide and call correctly.

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 both ticker and days are already documented with ranges and defaults. The description only alludes to the window ('for the window') without adding format or boundary detail, so the 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 pins the exact data source (SEC Form 4 filings, one row per transaction). This cleanly separates it from siblings like get_sec_filings and get_sec_8k, which cover different filing types.

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 is clear routing guidance. It does not name an alternative tool or state when-not-to-use, so it falls short of the top score.

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