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

Annotations already cover read-only and open-world behavior, but the description adds genuinely non-structured information: a per-call cost of $0.006 USDC via x402. That pricing disclosure is material for tool selection. It stops short of 5 because it says nothing about rate limits, error behavior, or how many filings are returned by default.

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 resource and its payload before the pricing note. The first sentence is long and list-like but every element earns its place by describing the return payload. 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 no output schema and only one of two params documented, the description carries real burden and does well: it enumerates the returned fields including derived ones (net buying/selling summary, 10b5-1 plan flags) and discloses cost. It lacks coverage of history depth, pagination, and ticker formatting.

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 50%: 'limit' is documented in the schema as 1-30, but 'ticker' has no description at all. The phrase 'any US public company' implicitly signals a ticker symbol, which partially compensates, but the description adds no format guidance (exchange suffix, case, symbols vs names). Baseline 3 is appropriate.

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 resource and source: insider trades at US public companies from SEC Form 4 filings, listing the exact fields returned (who, buy/sell, shares, price, value, holdings after, 10b5-1 flags). A sibling like 'filings' could plausibly overlap, and the description never clarifies the boundary, so it falls short of the top score.

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?

Usage is implied by the data described (you call it when you want insider transaction activity for a ticker), but there is no explicit when-to-use, no when-not-to-use, and no named alternative such as 'filings' or 'sec_events'. The agent must infer the routing decision.

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