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

Annotations already declare write/destructive/open-world=false, and the description adds real value beyond them: it states the rule is free, requires the 'act' scope, and describes downstream effects (morning marketing posts, move and voice reads, visibility in Memory). It does not, however, address the destructiveHint=true flag – whether recording a rule can overwrite or conflict with existing rules is never explained.

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 core action and scope boundary, then the WHEN gate, then constraints and cost. Dense and mostly waste-free, though the sentence listing downstream surfaces ('move and voice reads carry it') is the one place phrasing is heavier than needed.

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 one-parameter write tool with an output schema absent and annotations present, the description covers trigger, scope requirement, cost, and effects. The remaining gap is the destructive/replacement semantics flagged by the annotations, which an agent should know before writing.

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% for the single 'text' parameter, so the baseline is 3. The description adds a constraint not in the schema's own enum/form: 'One sentence. At most 12.' (presumably words), tightening the loosely bounded 10–200 char limit, though the unit of '12' is left slightly ambiguous.

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 and resource (save a writing rule) and immediately draws the scope boundary that matters: into the person's OWN voice, never the brand's. That distinguishes it from siblings like set_voice_axes and get_voice_profile, which operate on the brand voice.

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 WHEN clause: only after the person approves it in words, with a concrete example (a yes to a rule proposed from how they edited a draft) and an explicit exclusion (never record one they did not approve). There is no ambiguity about the trigger condition.

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