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

Annotations already cover the safety profile (readOnly, non-destructive, closed world), so the description's contribution is return-shape detail: ordering (newest first), presence of an in-progress restore, and the pitr.earliestAt/pitr.savedUpTo span. That is genuinely useful since no output schema exists. It does not mention pagination or whether empty lists occur.

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?

A single compact sentence with no wasted clauses, and the most important fact (newest first) is front-loaded. The phrasing is a noun fragment and 'the span it can be restored to any second of' is slightly convoluted, costing a point.

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 with no output schema, the description adequately explains what comes back, including conditional behavior for databases. The main gap is the absence of any pointer to restore_backup or to what to do with the returned backup identifiers.

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?

One parameter with 100% schema coverage, and the schema already explains it is the service id obtained from list_services. The description adds no further meaning about the id, 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?

The title supplies the verb ('List') and the description states the exact resource and its shape: a service's backups, newest first, plus any in-progress restore and the PITR window for databases. An agent can tell this apart from back_up_service / restore_backup, though the description itself never names those siblings.

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?

Usage is only implied: the schema note 'from list_services' hints at the call sequence, and the mention of restore state hints that this is the inspection step before restore_backup. There is no explicit when-to-use, when-not-to-use, or named alternative.

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