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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false), so the description's job is to add context beyond that. It does: sort order is disclosed, prices are live USD, each result carries a rent link, and 'next_step says how to rent one.' It also surfaces non-obvious node semantics (tier secure/spot, min_gpus_per_rental meaning some nodes rent only whole). Only the exact response shape/pagination behavior is left vague.

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?

Three dense sentences, front-loaded with what the tool returns and the ordering, then usage routing, then extra result fields. Every clause carries information, though the third sentence packs several concepts (tier, reliability_score, min_gpus_per_rental, next_step) tightly.

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?

No output schema exists, so the description must carry return semantics, and it does: ordering, live prices, rent link, tier, reliability_score, min_gpus_per_rental, next_step. Complete enough for a flexible 5-param filter tool; only result-count/pagination behavior is unspecified.

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 the baseline is 3 and the schema already documents every parameter including examples and ranges. The description echoes the filter set (GPU model, count, country, price cap) without adding syntax or constraint detail beyond the schema.

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?

States a specific verb (List), resource (rentable GPU nodes on Lium), ordering (cheapest per GPU-hour first), and explicitly contrasts itself with the sibling get_gpu_prices. An agent can distinguish this from every other search/pricing sibling without opening the schema.

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 names the trigger condition (user wants a specific machine: GPU model, count, country, price cap) and routes the alternative case to get_gpu_prices. This is textbook when/when-not guidance with a named alternative.

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