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

Annotations already declare that this is a non-read-only, non-destructive, non-idempotent write with no open-world access, so the safety profile is covered. The description adds the free-text nature and the timestamp fallback ('omitted for now'), but says nothing about the third parameter, storage side effects, or how to avoid duplicates.

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?

A single compact sentence with the content-type qualifiers and the timestamp rule tucked into one parenthetical. The phrase 'omitted for now' is terse to the point of ambiguity, but nothing is wasted.

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 write tool with no output schema, the description conveys the core contract and the annotations cover mutation safety. It omits any explanation of idempotency_key, return shape, or what the note attaches to beyond the vague 'timeline'.

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 0%, so the description carries the full burden. It gives meaning to 'text' (free-text note) and 'at' (ISO timestamp, with omission apparently meaning 'now'), but leaves 'idempotency_key' entirely undocumented in both schema and description. Partial compensation for a genuine coverage gap.

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+resource ('Log a free-text note') and scopes the content with concrete examples (observation, behaviour, symptom), which separates it from the structured siblings log_feed, log_sleep, log_nappy and log_measurement. It stops short of naming any sibling explicitly, so an agent must infer the boundary itself.

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 parenthetical content examples ('an observation, a behaviour, a symptom') imply when this tool applies, but there is no explicit when/when-not and no mention of alternatives such as 'remember' or 'log_measurement' for numeric data. Usage is left to inference.

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