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

Goes well beyond the annotations, which only cover the read-only/idempotent safety profile. It discloses subtle methodological rules: only superinvestors filing both quarters are compared, added/reduced is decided by share count not value, split adjustments via split_factor, ticker/CUSIP merging, and the 45-day 13F filing lag. This is exactly the kind of non-obvious behavior an agent needs.

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?

Dense but front-loaded, leading with the core purpose before detailing edge cases. The long run-on sentences pack a lot of caveats, but each sentence carries substantive information rather than 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?

Given an output schema exists, the description need not explain return values, and it covers the remaining gaps: modes, defaults, and the accounting/matching methodology. An agent has everything needed to invoke 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 baseline is 3, but the description adds real meaning: it explains that quarter compares against the previous calendar quarter and what the superinvestor_cik switch actually changes (grouping by action, largest first, shares_change_pct in percent). This 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+resource ('what curated superinvestors bought and sold in one quarter according to 13F') and delineates two distinct output modes based on superinvestor_cik. This is precise enough to distinguish it from siblings like get_stock_13f_holders or list_superinvestors 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?

Explicitly explains the conditional branching: omit superinvestor_cik for the cross-investor summary, provide it for individual moves. It also clarifies the default quarter behavior. It does not name a specific alternative tool for looking up a CIK, but the usage context is clear.

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