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

Annotations already declare this is a non-destructive write (readOnlyHint false, destructiveHint false, openWorldHint false), so the safety profile is known. The description adds the precondition and the source of the data, but says nothing about what happens on repeated calls despite idempotentHint=false, and the trailing sentence "Does not use a tool call of the month" is opaque and conveys no usable behavior.

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?

The precondition is front-loaded in the second sentence and the purpose statement leads. The final fragment about a "tool call of the month" is unearned noise that should be cut or rewritten.

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 two-parameter write tool with a fully documented schema and annotations covering the safety profile, the description supplies the one thing structured fields cannot: the conversational precondition for calling it. No output schema is needed for a void-style recording action.

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%, including an enum for reason and a 500-char cap on details, so the schema does the heavy lifting. "In their words" lightly reinforces the details field but adds no mapping guidance for choosing among the five reason values.

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: records why the user is not upgrading to the Unlimited plan, and it clarifies the content is the user's own words. It does not explicitly distinguish itself from the related sibling plan_status, which an agent might otherwise consider.

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?

"Call it only after the user answered the question about what is stopping them" is an explicit, checkable precondition for invocation. It stops short of naming alternatives or explaining when not to record, but the timing guidance is concrete.

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