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

Annotations already declare readOnly/idempotent/closed-world, so the safety profile is covered. The description adds genuinely new behavioral facts: results are restricted to active SKUs, data comes from a daily archive rather than live fetching, and each row carries verified_at, a stale flag and source_url — which tells the agent how fresh and trustworthy results are.

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?

Four short sentences, front-loaded with what is searchable and in what dimensions, then constraints, then return shape, then provenance. No filler and nothing redundant with the schema.

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 compensates by enumerating the key return fields (current list price, unit, currency, verified_at, stale, source_url). Minor gaps remain: pagination/limit behavior and the default ordering are only discoverable from the schema, not the description.

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 coverage is 100%, so baseline is 3, but the description adds value the schema lacks: it spells out the category values (vps|gpu|llm) even though the schema declares category as an untyped string with no enum, and clarifies that query is a substring match on name or id.

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 (Find) and resource (VPS plans, GPU instances, LLM models) plus the three filter axes, so an agent knows exactly what is searchable. It does not name a sibling to differentiate from (e.g. get_price vs cheapest_for_spec), so it stops short of a 5.

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?

"Active SKUs only" and "reads the ledger's own daily archive, nothing is fetched live" give real usage context, and the implicit browse-all case is covered by the query parameter. However, there is no explicit when-to-use-this-instead-of guidance relative to get_price, list_changes or cheapest_for_spec.

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