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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds value beyond that by stating the data is live ('right now') and enumerating the returned fields, which matters because no output schema exists. It does not mention pagination or any auth/rate-limit behavior.

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 short sentences, zero filler. The capability and its return contents come first, and the downstream usage instruction follows.

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 no output schema, the description carries the burden of describing returns, which it does (VRAM, class, cheapest hourly price per GPU). Combined with the gpu_slug handoff to search_offers, an agent has enough to call it correctly, though freshness/pagination behavior is unstated.

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 100%, so both parameters (query, min_vram_gb) are already fully documented in the schema with examples and constraints. The description adds no filtering syntax or additional parameter meaning, so the baseline 3 applies.

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?

Specific verb+resource ('list GPU models available on gpu.nz') plus the returned fields (VRAM, class, cheapest hourly price) and a live scope ('right now'). It also implicitly distinguishes itself from the sibling search_offers by positioning itself as the upstream lookup for gpu_slug.

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?

'Use it to pick a gpu_slug for search_offers' gives an explicit workflow context and names the downstream sibling. There are no when-not conditions or exclusion rules, but for a read-only catalog lookup the routing guidance is clear.

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