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

Annotations only indicate read-only and non-destructive behavior. The description adds substantial behavioral caveats: the legacy Total Shares field is not a pure share count, changes are withheld when a filer lacks a 13F in either compared quarter, missing filings are not trades, values may fall back or be zero, and non-ETF stocks use a provisional combined view during the open filing window. This is exactly the kind of disclosure needed to prevent misinterpretation of results.

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 description is long but every sentence carries operational meaning, from the non-pure share count warning to valuation fallbacks and the provisional combined view. The main purpose is front-loaded, and the caveats are essential for correctly interpreting the data. There is no filler or repetition of annotation facts.

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?

Since there is no output schema, the description names the returned fields (total reported quantity, published position value, and filer count) and explains important edge cases like withheld changes and valuation fallbacks. It also addresses the newest-quarter filing window behavior, so an agent knows what to expect without needing additional lookups. This is complete for a two-parameter read-only query.

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 description coverage is 100%, so both parameters are already documented in the input schema. The description reinforces that the ticker must be an exact listed security and that results span quarterly periods, but it does not add new syntax or format details beyond the schema. Baseline 3 is appropriate when the schema already carries the parameter documentation burden.

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: getting the historical trend of aggregate reported 13F exposure for an exact stock or ETF listing across multiple quarters. It clearly distinguishes this from institution-level or market-wide 13F tools by focusing on one listing's history over time. The title alone would not provide this specificity.

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?

Establishes clear usage context: this tool is for historical aggregate ownership trend of a single exact ticker or ETF, not for a particular institution's portfolio or market-wide activity. It does not explicitly name sibling alternatives or state when-not-to-use conditions, but the scope is specific enough that an agent can select it appropriately.

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