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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds a genuinely new behavioral fact — the required instances:read scope — plus a sketch of the return payload (status, GPU, price, SSH command), which matters because there is no output schema. It omits pagination/rate-limit behavior, keeping it short of a 5.

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, front-loaded sentences with no filler; the payload contents come first and the permission requirement last. The telegraphic phrasing borders on under-specification rather than true economy, which keeps it from a 5.

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 one-parameter, read-only list tool with no output schema, the description supplies both the permission needed and the shape of the returned rows, which is most of what an agent needs. The one real gap is that it says nothing about result volume or pagination for a potentially long server list.

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?

There is a single optional parameter with 100% schema description coverage, including the enum values and the default (active) versus destroyed-inclusion semantics. The description adds nothing about status filtering, so the schema-baseline of 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?

Combined with the title, the description identifies the resource ("Your rented servers") and enumerates what each entry carries (status, GPU, price, SSH command), so it reads clearly as a list-instances tool. It does not explicitly contrast itself with the single-instance sibling get_instance or with search_offers, so sibling differentiation is only implicit.

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?

"Needs instances:read" states a permission prerequisite, which is useful invocation guidance, but the description never says when to prefer this over get_instance or when filtering by status is appropriate. Usage is essentially implied by the tool name, with no exclusions or alternatives named.

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