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

The description goes beyond the annotations by specifying that results are ordered heaviest first, include the holdings date and source (issuer daily file or SEC filing), and return the largest holders plus the total count. This adds behavioral context about output format and data provenance, which is valuable for an agent deciding whether to rely on the results. The readOnlyHint and idempotentHint are consistent with the described read-only behavior.

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 a single, dense sentence that front-loads the core purpose and then adds key details (ordering, holdings date, source, largest holders, total count). It is efficient with no wasted words, though it could be split into two sentences for readability without loss of information.

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 with only two parameters and no output schema, the description adequately covers what the agent needs to know: what it returns, the ordering, and the source of the data. It does not mention pagination or error behavior, but these are minor for a read-only tool with a 'top' parameter that likely controls pagination. The description is sufficient for an agent to call 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?

The input schema already documents both parameters (ticker and top) with clear descriptions, achieving 100% schema description coverage. The description adds minimal extra meaning beyond confirming that ticker refers to a single stock; it does not provide format details or examples beyond what the schema offers, so the baseline of 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?

The description clearly states the tool's function: given one stock, it returns the US ETFs that hold it, along with the weight in each, ordered heaviest first, plus the holdings date and source. It uses a specific verb (returns) and resource (covered US ETFs), and distinguishes itself from siblings like look_through (which likely shows a fund's holdings) by focusing on a stock's exposure across funds.

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 implicitly conveys when to use the tool (when you need to know which ETFs hold a stock and at what weight), but it does not explicitly mention alternatives or conditions for not using it. There is no guidance on choosing between this and sibling tools like compare_funds or look_through, so the agent must infer the appropriate context.

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