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

Annotations already cover safety (readOnly, idempotent, closed-world), so the description's job is to add domain behavior — and it does, by restricting scope to 'open-market PURCHASES', which implicitly excludes grants, option exercises, and gifts. It adds no notes on data lag or coverage limits, but for a read-only scan that is a minor gap.

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: the first front-loads scope and the ranking modes, the second is a compact list of example queries. No filler, and every clause maps to a parameter or a selection decision.

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 and full parameter documentation, the definition covers what an agent needs to invoke it. The one omission against a crowded sibling set (find_insider_clusters, find_emerging_insider_buying, get_insider_signal) is a routing rule that separates this market-wide scan from those narrower tools.

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%, so baseline is 3; the description earns above that by explaining the meaning behind two non-obvious parameters — sort_by is framed as total value / distinct insiders / recency, and min_insiders is glossed as 'cluster buying' with a worked example of 3+ insiders.

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 gives a specific verb and resource (scan U.S. companies for insider open-market purchases) plus the ranking modes, and the phrase 'ALL U.S. companies' signals a market-wide scan rather than a single-company lookup. It stops short of naming the very similar siblings find_insider_clusters and find_emerging_insider_buying, which would have made the distinction airtight.

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?

Three concrete example phrasings ('which insiders are buying right now?', 'CEO purchases this month', 'companies where 3+ insiders bought') give an agent clear triggering contexts. There are no exclusions, so nothing tells the agent when to prefer find_insider_clusters or get_insider_activity instead.

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