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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false; the description goes beyond them by disclosing replacement semantics ('each replaces what is there', 'topics replaces the whole list') and reversibility ('One call is one change the writer can undo'), which links it to undo_voice_change. It is also candid about the style-only limit (no invented facts, stories, quotes, or numbers). It does not explicitly state permission/workspace requirements for mutation, though the schema hints at them.

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?

Front-loaded with the action and the section list, then the operational rules, then the constraint. Every sentence carries a distinct rule; the style-only caveat is slightly compressed but not wasteful.

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?

With annotations, full schema descriptions, and an output schema present, the description supplies exactly the missing pieces: trigger context, partial-update semantics, replacement behavior, and undo-ability. An agent has enough to call it correctly without further inference.

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%, so the schema already documents every parameter including the empty/null clearing behavior and the topics-replaces-list rule. The description reinforces replace semantics but adds no syntax, format, or length guidance beyond the structured data, 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?

States a specific verb (Set) and resource (sections of the writer's voice profile) and enumerates exactly which sections are editable (how they sound, niche, audience, instructions, topics). This lets an agent distinguish it from siblings like update_voice_rule, update_voice_stances, and update_voice_examples without opening their schemas.

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?

Explicit trigger condition ('when the writer asks you to'), explicit partial-update instruction ('Pass only the sections to change'), and an explicit prohibition ('never fill a section in on your own'). It also distinguishes scope from related tools by naming the section set it owns.

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