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

Description adds context beyond annotations: topics are curated, federally-sourced, audience-safety-checked, and the corpus stays internal. No contradiction with readOnlyHint annotation.

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?

Two sentences with no waste. First sentence states purpose, second gives usage guidance and limitation. Front-loaded and efficient.

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 output schema covering return values, the description explains the content of the topics and their purpose, providing a complete picture for a zero-parameter 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?

No parameters, so description doesn't need to explain them. It adds value by describing the nature of the returned topics (curated labels from a corpus). Baseline for 0 params is 4.

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 verb 'List' and the resource 'curated sandbox topic labels', and distinguishes from siblings by noting it does not enumerate messages and is for previewing content domains before creating a stream.

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?

Explicitly says 'Use it to preview what content domains exist before creating a stream' and warns 'Does NOT enumerate messages'. Also directs to an alternative resource for full catalog and gating contract.

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