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

Annotations declare destructiveHint=true and readOnlyHint=false, so the agent knows this is a mutating operation. The description adds nothing beyond that: it doesn't say whether updates merge with or replace existing preferences, whether omitted keys are preserved, whether this requires auth or elevated permissions, or whether changes are reversible. For a destructive mutation, this leaves real gaps.

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?

One short, front-loaded sentence with no filler or repetition. It is efficient, though the brevity contributes to the gaps noted elsewhere.

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?

An output schema exists so return values need not be described, but for a destructive mutation with a completely opaque free-form parameter object, the description should at minimum indicate what preference keys are accepted and whether the update is partial or full. Neither is covered.

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%, and the single parameter is a free-form object with additionalProperties=true and no declared properties. The description mentions 'selected preferences' but never enumerates or hints at valid keys or value formats, so an agent has no way to construct a correct call.

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 names a specific verb and resource (update user preferences), which is clear enough, but 'selected preferences' is vague and it does nothing to distinguish this tool from the close sibling get_user_settings or update_unit_settings. An agent must open the schema to learn anything about scope, and the schema itself reveals nothing.

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?

The description gives no when-to-use guidance, no prerequisites, and no mention of any alternative despite update_unit_settings and get_user_settings sitting in the sibling list. Nothing tells the agent whether this is the right tool for preferences vs. unit settings.

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