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

Annotations already cover read-only, idempotent, and non-destructive behavior, and the description does not contradict that. It adds useful behavioral context by detailing the return contents (rank, score, description, confidence, canonical URL, selected niche, resolution explanation) and by warning against hallucinating results, which goes beyond the 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 four tight sentences with no filler. It front-loads the core purpose, then efficiently covers return values, routing guidance, and an important anti-hallucination constraint. Every sentence earns its place.

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 tool with only two parameters and no output schema, the description is remarkably complete: it explains what the tool returns, how to route to find_niche, when it can resolve natural language itself, and what the agent must not do. Nothing essential for correct invocation is missing.

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 already describes both parameters fully, including the niche slug/natural-language dual meaning and the limit range, so the description adds limited new semantic value. It reinforces the natural-language option and 'verified' nuance but does not materially exceed the schema's coverage.

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 ('Fetch'), a specific resource ('ranked Lunoo results'), and the input format ('verified niche slug or natural-language request'). It clearly differentiates from siblings by naming find_niche and noting this tool can resolve natural language itself, so an agent can distinguish it from get_item and find_niche.

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 'Prefer calling find_niche first', giving the preferred alternative and the fallback condition. It also instructs the agent to cite the returned ranking URL and avoid inventing items, scores, or slugs, which is actionable usage guidance.

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