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

With no annotations, the description carries the burden of behavioral disclosure. It discloses that the tool is free to use, which is valuable cost-related behavior. It also highlights that it reports freshness of each corpus, giving context about the data quality. This goes beyond a bare 'list' statement.

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 two sentences, extremely concise, and front-loaded. The first sentence conveys the core function; the second adds a critical cost directive. No wasted words.

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 zero-parameter, no-output-schema tool, the description is sufficiently complete. It specifies what is listed (niches) and includes freshness information. The reference to tiktok_hooks provides contextual linkage. It could have stated output format, but for a simple list tool this is not a significant gap.

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 input schema has zero parameters, so the baseline for this dimension is 4. The description adds no parameter-specific details because there are none, but it does not need to compensate for any schema gaps since there are no parameters.

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: 'List the niches tiktok_hooks can report on, with how fresh each corpus is.' It uses a specific verb ('List'), names the resource ('niches'), and ties it to a sibling tool ('tiktok_hooks'), which distinguishes it from other listing tools.

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 implies usage: an agent should call this to discover available niches before using tiktok_hooks. The second sentence, 'Free — an agent should not pay to learn what it may ask for,' explicitly advises using this free tool instead of paying elsewhere, which serves as a clear usage guideline.

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