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

No annotations are provided, so the description carries the full burden. It discloses the paid nature, the required CIK, and the exact payment protocol. However, it does not describe the return format or any rate limits, leaving some behavioral opacity, but the critical payment behavior is well covered.

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 sentences, front-loaded with the core function, followed by prerequisites and payment details. No filler or redundant phrasing; every sentence serves a purpose.

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?

The description covers the purpose, prerequisites, and payment settlement clearly. With no output schema, it adequately hints at the returned data ('bought, sold, added, trimmed'). It could mention response structure explicitly, but for a paid data call with a well-defined payment flow, this is sufficient.

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%, with detailed descriptions for both `cik` and `x_payment`, including the payment flow in `x_payment`. The description adds little beyond restating the CIK requirement and the payment process already explained in the schema, 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?

The description clearly states the tool shows an institutional manager's quarter-over-quarter changes (bought, sold, added, trimmed) and labels it the 'whale-watch view.' This specific verb+resource+scope distinguishes it from siblings like `pricing`.

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?

The description explicitly explains the paid two-step payment flow: call without x_payment to receive terms, sign them, then call again with x_payment to get data. It also points to the free `pricing` tool as an alternative for price listings, providing clear when-to-use guidance.

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