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

Annotations already declare the safety profile (readOnlyHint=false, destructiveHint=false, idempotentHint=true). The description adds genuinely new behavioral context beyond them: each call is a single, undoable change, which connects the agent to undo_voice_change. It does not, however, describe what happens on duplicate adds or partial failures.

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?

Three dense sentences, front-loaded with the operation and its scope, with no repetition of schema or annotation content. Each sentence carries a distinct rule (what, how to source text, where ids come from, reversibility).

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?

Output schema is present, so return values need no explanation, and annotations cover the safety profile. For a mutation tool with full schema coverage, the remaining description burden is the sourcing rule and undoability, both of which are supplied.

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 baseline is 3. The description goes beyond it by constraining the semantics of the free-text 'add' payload (must be the writer's own words, never inferred) and by explaining the provenance of the 'remove' ids, which the schema alone does not convey.

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 pair (add/remove) and a precise resource (stances in the writer's voice profile), then defines the two stance kinds inline. This cleanly separates it from siblings like update_voice_profile, update_voice_rule, and save_voice_preference without needing to open the schema.

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?

Gives a real usage rule ('Add only stances the writer has stated in their own words; never infer one') and routes id acquisition to get_voice_profile. It stops short of naming the closest alternative tools (e.g. update_voice_rule) or stating when not to use this one, so it is clear context but not full alternative routing.

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