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

With no annotations, the description carries full burden and excels: it discloses storage billing implications, clamping behavior, response reflects actual stored values, sentinel -1 meaning, reset flag semantics, and the required write scope. This is exemplary transparency beyond the schema.

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?

Every sentence is purposeful and information-dense. The description is compact (three short paragraphs) yet covers purpose, constraints, special values, permissions, and return shape without redundancy.

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?

Despite lacking annotations and an output schema, the description provides sufficient context for safe invocation: prerequisites (write scope), mutation behavior (clamping, response actuals), special sentinel semantics, and return structure. Slight gap: no mention of which knobs exist beyond the generic 'knob', but the schema covers parameter names. Overall very complete for a mutation tool.

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 0%, so the description must compensate. It adds essential semantics: -1 leaves a knob unchanged, reset=true restores defaults, and values are clamped (impacting how keep_* parameters are interpreted). It does not describe slug explicitly, but the term is self-explanatory and required.

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 description clearly states the verb 'Set' and the resource 'backup retention policy for a VPS site.' It distinguishes this from the sibling get_backup_retention by focusing on mutation and policy configuration.

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?

Provides context on when to use this tool (to adjust retention) and important cost/behavior considerations (billing on stored bytes, clamping). It implies a read alternative exists via get_backup_retention but does not explicitly name it as an alternative for viewing current settings.

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