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

With no annotations provided, the description carries the behavioral burden. It discloses that the data comes from a frozen dated archive, covers pieces written that night, and is not a per-fund lookup. It could go further by describing the response shape, but for a simple archive retrieval it is reasonably transparent.

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 four short sentences, each earning its place: function, usage condition, input format, and scope caveat. It is front-loaded and contains no filler or repetition.

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 one-parameter tool with no output schema, the description is complete: it explains what the tool returns, when to use it, how to format the date, and a key boundary. Nothing necessary for correct invocation is 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?

The only parameter, date, has no schema description and 0% schema coverage. The description fully compensates by specifying the exact format 'YYYY-MM-DD' and clarifying that the date selects what ETFIQ published on that date. This is far more than the input schema alone provides.

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: retrieving what ETFIQ published on a given date from a frozen dated archive. It also differentiates itself from sibling tools by noting that every other tool answers about today, making the temporal scope unmistakable.

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 explicitly says when to use the tool: for past-date questions or when a figure needs to remain stable after being quoted. It also contrasts with 'every other tool here' and includes an exclusion ('not an arbitrary per-fund figure on an arbitrary day'), which helps an agent route correctly.

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