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

Annotations already declare this a safe, idempotent, closed-world read. The description adds genuine context beyond that: the data source and its $100M+ AUM reporting threshold, the quarter-over-quarter comparison basis, and a tier-gated output difference ('Analyst and Edge also get the lists of new funds, sold-out funds, biggest adds and biggest cuts'). It says nothing about data lag or filing latency, which matters for 13F data.

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?

Front-loaded with the core answer ('Who owns a stock...') and then the return fields, with example queries last. The first sentence is long and clause-heavy but nearly every clause carries distinct information; the tier note is a minor digression mid-payload.

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 needn't explain return formatting, and it still covers source, scope, tier differences, and query intents. An agent has everything needed to decide to call this and pass a ticker 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% and both parameters are documented in the schema, including the 5–25 range and default 10 for 'top'. The description only references 'top holders' loosely and adds no syntax or nuance beyond 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?

States a specific verb and resource ('Who owns a stock, from SEC Form 13F filings') and enumerates the exact data returned: holder count, ownership share, top holders with QoQ change, and open/add/cut/sold-out counts. It is clearly distinguishable from the inverse sibling get_fund_holdings, which looks up a fund's positions rather than a stock's owners.

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?

Provides four concrete example phrasings ('who owns PLTR?', 'are funds buying or selling NVDA?', 'top institutional holders', 'did hedge funds add last quarter?') that map user intent to this tool. It does not, however, name an alternative or state when not to use it versus get_fund_holdings or get_congress_trades.

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