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

Annotations already declare readOnlyHint and destructiveHint, but the description adds valuable behavioral details: the data source is the latest NPORT-P, results are sorted largest-first, and coverage is conditional ('full, tracked U.S. equities only, or unknown') depending on availability of the authoritative reported count. This goes beyond what annotations convey.

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?

Three tightly written sentences, with the core purpose and data source in the first sentence. Every sentence carries useful information and there is no filler or repetition of schema details.

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 read-only listing tool with fully documented parameters and safety annotations, the description is complete. It explains the source, sorting, coverage behavior, and pagination approach, so an agent has enough context 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?

Schema description coverage is 100%, so the parameters are already fully documented. The description adds a small behavioral note about offset for broad portfolios and ordering context, but does not substantially expand parameter semantics beyond the schema.

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 states a specific verb ('Get'), a resource ('an ETF's stored portfolio holdings'), a source ('latest SEC Form NPORT-P report'), and the ordering ('largest position first'). This clearly distinguishes it from sibling tools like GetFundsHoldingStock or GetTopHolders.

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 gives clear context: it covers ETF portfolio holdings from the latest NPORT-P, with coverage caveats, and explicitly tells the user to use 'offset' for broad portfolios. It does not explicitly name alternative tools or exclusion cases, but the use case is clear enough for agent selection.

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