hydra_preview_data

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds that the tool returns only columns and first rows, which is some behavioral context, but it does not disclose limits, error cases, or behavior on unsupported files beyond what annotations provide.

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 concise and front-loaded: it states the core capability first, then adds high-value usage timing. Every sentence earns its place, and no redundant or filler content is present.

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 simple two-parameter preview tool with an output schema available, the description gives enough context to invoke it correctly: what it previews, which formats it supports, and when to call it. It could be more complete by explaining the row parameter and any file-access requirements, but the low complexity and existing annotations reduce the need.

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 0%, so the description must compensate, but it only hints at parameter meaning: file_path is a data file of certain formats and rows relates to 'first rows.' It does not clarify the row-count semantics, default behavior, or path expectations, leaving the agent to rely on the schema's minimal titles.

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 a specific action ('Show the columns and the first rows'), a clear resource ('data file'), and accepted formats (CSV, JSON, Parquet). It clearly distinguishes this from sibling tools by focusing on previewing data rather than listing, writing, or running jobs.

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 to call this 'BEFORE writing a job' to learn column names and 'AFTER a run' to check results, giving clear situational guidance. It does not explicitly name alternatives or state when not to use it, so it falls just short of a full 5.

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