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

Annotations already declare readOnlyHint=true, so safety is covered and the bar is lower. The description adds the useful framing that the results are bootable/restorable rather than raw records, but says nothing about pagination behavior or default result size for a 6-filter listing.

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 compact sentences with zero filler; the purpose is front-loaded and the endpoint reference is a terse second clause.

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?

Adequate but thin for a filterable list tool with no output schema. All inputs are covered by the schema, but the description does not note that results are paginated or what shape an image record takes, leaving the agent to discover this at call time.

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% with all six optional filters (name, type, architecture, label_selector, page, per_page) documented inline, including enum values and the Hetzner label idiom. The description adds no parameter-level meaning, so 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 ('List') and resource ('OS images, snapshots and backups'), plus the added semantic gloss that these are bootable/restorable. It is clearly distinct from the mutating sibling hetzner_create_image_from_server, though it does not name that sibling explicitly.

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?

No when-to-use guidance, no stated prerequisites, and no mention of alternatives such as hetzner_get_server when an agent wants images attached to a specific server. The API endpoint reference (GET /images) is context, not usage guidance.

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