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

Annotations already cover read-only/idempotent/non-destructive, and the description adds substantial non-obvious behavior: split handling with split_factor and CUSIP changes, the 0.5% unchanged threshold, a 200-holding cap requiring pagination, exclusion of options from portfolio value, null url for tickerless securities, and suppression of changes when the prior quarter was not filed.

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 core purpose and defaults are front-loaded, and every clause carries real information rather than repetition. It is dense to the point of reading as one long block, which slightly hurts scannability, but there is no filler to cut.

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?

For a tool this complex, the description covers the edge cases an agent must know before calling: pagination limits, split adjustments, missing-prior-quarter behavior, and option/sold-out reporting. Return fields are also covered by the output schema, so nothing material is missing.

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 baseline is 3, but the description adds meaning about how parameters interact: the quarter parameter's default (latest filed) is tied to the change/sold-out logic, and the page hint is linked to the 200-holding cap. This slightly exceeds what the schema alone conveys.

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: retrieving one 13F filer (institution or curated superinvestor) by SEC CIK, plus its filing quarters and holdings. The scope is narrow and unambiguous enough that an agent can distinguish it from siblings like get_stock_13f_holders (the inverse direction) 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?

The description never says when to use this tool versus get_stock_13f_holders, get_superinvestor_activity, or search; the only routing hint ('Get it from search') lives in the schema, not the description. Usage is inferable from the resource name alone, but no explicit conditions or exclusions are given.

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