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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered, and the description still adds real behavioral context: the download link is one-time and only appears once the fill is done, and defaults to the latest fill. It does not clarify link expiry duration or what happens on a failed fill.

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?

A single front-loaded sentence with no filler; the return contents come first and the default-fill behavior is folded in compactly. The nested parenthetical '(or a given) one's' is slightly awkward but does not cost meaningful clarity.

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?

With no output schema, the description carries the full burden of explaining return values, and it only sketches them (status, row counts, link). It never enumerates possible status values or describes behavior on failed/in-progress fills, which is the key gap for a status-polling tool.

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, including fill_id defaulting to the latest. The description only echoes that default behavior rather than adding syntax or constraint detail, which matches the baseline 3 when the schema does the heavy lifting.

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 names the resource (a model's fills) and precisely what it returns: status, row counts, and a one-time download link. It is clear but never distinguishes itself from the sibling read_fill_results, so an agent must infer the boundary between checking a fill and reading its results.

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?

There is no when-to-use or when-not-to-use guidance, and no routing to alternatives such as read_fill_results or job_status. The polling intent is only inferable from the fact that a 'status' is returned, which is weak guidance for a multi-sibling workflow.

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