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

Annotations already establish this as a safe, read-only, deterministic query. The description adds meaningful behavioral context beyond that: the <5-insider threshold, the crowded 5+ counterpart, and the fact that pace is measured by comparing recent activity with earlier activity. The only small gap is the meta-claim that it 'Explains exactly how rising is measured' without explaining that formula in the description itself.

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?

The purpose and classification criteria are front-loaded in the first sentence, followed by usage examples. It is efficient overall, though the sentence 'Explains exactly how rising is measured' is slightly meta and does not itself deliver the explanation it promises.

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 description need not explain return values. It supplies the key selection logic, the emerging-versus-crowded distinction, and usage intents, leaving no material gap for an agent to call it 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 coverage is 100%, so the schema already documents all four parameters, including the relationship between recent_days and the earlier part of the window. The description adds only contextual framing ('in the window', 'recently than earlier') rather than parameter syntax or constraints beyond 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?

The description states a specific verb and resource ('Spot insider buying') and defines the exact selection criteria: fewer than 5 insiders with a rising pace versus 5+ insiders for crowded companies. This lets an agent distinguish it from generic insider-buying or cluster tools without opening the schema.

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?

It gives clear usage contexts with quoted example questions ('which stocks have early, increasing insider buying...', 'emerging insider signals'). It implicitly contrasts with crowded buying but does not name a specific sibling tool to use instead when the user wants crowded names.

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