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

Annotations already declare readOnly/idempotent/non-destructive, and the description goes well beyond by disclosing data-freshness semantics (a quarter is complete only after the 45-day filing deadline; in_progress_quarter is still being filed), delisting behavior (active=false, delisted_on Form 25 date, last full 13F quarter), and why share classes are separate tickers. This is exactly the kind of state caveat an agent cannot infer from annotations.

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?

Purpose and the alternative-tool routing are front-loaded, and every clause carries substantive information rather than filler. The main cost is readability: the opening sentence is a single long chain of parentheticals, which makes scanning harder than it needs to be, but the density is largely justified by the tool's complexity.

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 the description need not explain return shapes, and it correctly spends its budget on the things structured fields cannot carry: quarterly completeness/timing, in-progress vs complete quarters, delisting edge cases, and share-class handling. An agent has everything needed to call this correctly and interpret freshness.

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% and the singular ticker parameter is fully documented in the schema, so the baseline is 3. The description adds real meaning beyond that by explaining that share classes (GOOG/GOOGL, BRK.A/BRK.B) are distinct tickers because 13F files each class separately, and by describing what happens when the ticker is delisted — useful semantics for interpreting the single input.

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?

Opens with a specific verb+resource ("Overview of one US-listed stock") and then enumerates the exact content blocks returned: SEC company facts, Form 4 P/S insider activity, 13F institutional ownership, and curated superinvestors. It explicitly names siblings (get_insider_trades, get_stock_13f_holders) as the source for the full lists, so an agent can separate this summary tool from them without opening any 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?

States when to route elsewhere: use get_insider_trades and get_stock_13f_holders for the full lists, implying this tool returns only aggregates. It also implicitly frames itself as a single-ticker overview. It does not, however, address other plausible alternatives such as get_institution or get_data_coverage, so the exclusions are incomplete.

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