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

Annotations already declare readOnlyHint=false and destructiveHint=false, so the description's added value is the fallback semantics (defaults only apply when nothing else names a model) and the per-family independence ('each family keeps its own default'). These are genuine behavioral traits not derivable from the annotations. It stops short of 5 by not addressing what clearing a default reverts to or any auth/scope constraints.

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?

It is short and each sentence carries information, so it is not padded. But the opening is a grammatically incomplete fragment that describes the resource rather than front-loading the action, which slightly obscures the tool's purpose at first read.

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 6-parameter edit tool with full schema coverage, no output schema, and annotations that cover the safety profile, the description supplies the missing semantics: fallback behavior and conditional parameter requirements. It is close to complete, lacking only error/reset behavior when a default is cleared.

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 coverage is 100%, so the per-parameter meanings are already documented (baseline 3). The description adds cross-parameter conditional requirements — 'voice_block needs provider' and 'segment_video needs talking_head' — which the flat per-parameter schema descriptions do not express. That is real added value beyond the schema.

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 ('Edit account') and the phrase 'The account's default model and settings for one kind of generation' together convey that this sets account-level defaults for a generation family. It is clearly distinguishable from siblings like editor_edit or segment_edit, which operate on other scopes. The opening is a noun fragment rather than an explicit verb+resource statement, so it stops short of a 5.

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?

'used when neither the call nor the item's prompt editor names one' explains the fallback context in which these defaults matter, which is useful. However, it never states when an agent should invoke this tool versus the many *_edit siblings, nor any preconditions for calling it. Usage is implied rather than directed.

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