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

Annotations only cover the read-only/idempotent safety profile, and the description adds substantial behavior beyond them: step-wise entered/exited/moved output with a 0.05-point threshold, inclusion of price moves rather than trades only, turnover measures, default to the latest step, coverage limited to stock ETFs read daily, and restated steps listing no trades. That is rich operational context an agent could not infer from structured fields.

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 trigger and scope, then edge cases, with no filler sentences. It is a dense single paragraph and a few clauses ('before and after, which includes price moves and not only trades, with the turnover measures') are convoluted, but every sentence carries 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?

An output schema exists, so return values need not be explained, yet the description still outlines the shape and covers the non-obvious cases (ETFs with no history, restated steps). Nothing an agent needs to call this correctly appears to be missing.

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%, so the baseline is 3, and the schema already documents limit and since thoroughly. The description adds one thing the schema does not: the default behavior of returning the latest step when no date is given, which clarifies how `since` is optional in practice.

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 precise verb and resource: returns the lines that entered/exited an ETF's holdings and the weights that moved, step by step. It explicitly distinguishes itself from get_etf_holdings (single-date holdings) and get_etf_holdings_history (overlap over time), so an agent can route without opening either 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?

Opens with an explicit trigger ('when the user asks what a US ETF bought, sold, added or dropped... recently or since a date') and closes with named exclusions pointing at the two sibling tools. When-to-use, when-not, and alternatives are all present.

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