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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, and the description adds meaningful context beyond those: no account needed, no query cost, same rows every time, default/max limits, and the distinction between row_count and total_row_count. No contradictions with annotations.

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 front-loaded with the core concept, then covers constraints, an example, return shape, and the routing alternative in a compact, organized way. Every sentence earns its place and there is no filler.

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, read-only tool, the description is complete: it explains what the sample contains, how many rows, how to invoke it, what is returned, what total_row_count means, and how to go beyond the sample. The absence of an output schema is fully compensated by the explicit return-field list.

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 carries the burden. It provides a concrete usage example for table_id and limit, states the default and maximum for limit, and explains the return fields. It largely repeats schema constraints for limit, but the example and return-field context compensate for missing schema descriptions.

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, resource, and scope: it samples rows from a public table, emphasizing it is a materialized preview and 'NOT a query'. It clearly distinguishes itself from the sibling query_table, so an agent can tell them apart without opening schemas.

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 tool explicitly says when to use it — for understanding shape and values — and gives an explicit when-not: 'To filter, sort, aggregate or read beyond the sample, use query_table, which needs a workspace key.' This names the alternative and the condition that selects it.

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