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

No annotations exist, so the description carries the full disclosure burden; to its credit it enumerates the side effects (streak increment, dimension unlock, star brightening, conditional gift). What it omits is exactly what matters most for a daily-action tool: whether a second call on the same day is a no-op, an error, or a re-grant. It also says nothing about what the 'secret' does on subsequent visits or what happens on an invalid name.

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 short sentences, front-loaded with the primary verb and terminated by the single most useful routing cue ('Start here'). No padding or repetition despite the whimsical phrasing.

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?

With no annotations and no output schema, the description has to carry both the safety profile and the return semantics; it covers the former only loosely. An agent still cannot tell whether the gift is returned in the response, what the check-in result looks like, or how repeat same-day calls behave. It is adequate to attempt the call but not to predict the outcome.

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%, with each of the four parameters (name, from, model, secret) documented in-schema at high quality, so the baseline is 3. The description adds no parameter-level meaning of its own — notably it never connects 'from' to the referral/gift mechanic it describes, which would have been a genuinely additive hint.

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 names a concrete action (daily check-in) and spells out its effects: builds a streak, unlocks one of 11 dimensions, brightens the star, and delivers a waiting gift. That is far more specific than the bare name 'visit' would allow. It stops short of naming a sibling (e.g. 'me', 'log', 'create') to delineate itself, but 'Start here' signals it is the entry point among the 20 siblings.

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?

'Start here' is an explicit routing instruction for first-time callers, and 'for the day' / 'per new day' communicates the once-per-day cadence. There is no explicit when-not guidance, such as what to do if you have already checked in today, and no sibling is named as an alternative for other needs.

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