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

Annotations already indicate non-readOnly behavior, and the description adds the useful detail that flexible time formats are accepted. However, it does not disclose other behavioral traits such as whether the created record is editable or how it interacts with related baby data.

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 description is two concise sentences that front-load the main action and include a key feature (flexible time formats). No unnecessary words or repetition of schema details.

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 simple log tool with full schema coverage and an output schema, the description is nearly complete. It clearly states the action and key input flexibility; only explicit guidance on when not to use it or how it differs from other create tools is missing.

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?

The input schema provides descriptions for all 4 parameters with 100% coverage, including detailed timestamp format guidance. The description's mention of 'flexible time formats' reinforces the schema but adds little beyond it.

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 description uses a specific verb ('Log') and resource ('nappy/diaper change'), which clearly distinguishes it from sibling tools like create_feed and create_sleep. The title 'Log Nappy Change' reinforces the purpose.

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?

The purpose is so specific that usage is implied, but the description does not explicitly state when to use this tool vs alternatives or mention any exclusions. No guidance is given for cases like recurring changes or integration with other baby logs.

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