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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is fully covered structurally. The description's real added value is the cost disclosure (10 credits, Tier 1) and the phase-pairing requirement, but it says nothing about return shape or whether recommendations vary by hemisphere/location.

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?

Two front-loaded sentences with no filler; the core function is stated first and the prerequisite second. The group/cost tags are structured metadata rather than prose padding.

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?

An output schema exists, so return values need not be explained, and annotations cover the safety profile. However, the description leaves the meaning of the required date and the sleep_cycles/moon-phase naming mismatch unaddressed, which an agent would need in order to invoke it confidently.

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 67%; the 'fields' and 'precision' params are self-documented, but the required 'date' param has no schema description and the description never clarifies whether it is the night of sleep or the date of phase lookup. With the schema doing most of the work, this sits at the baseline rather than compensating for the 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?

The description states a specific resource and output type ('Sleep recommendations per moon phase'), which is clear enough to distinguish it from the many other wellness siblings (diet, exercise, herbs, biorhythm). It does not, however, explicitly contrast itself with the closest alternative, astroway_calendar_moon_phase, or explain the 'cycles' framing in the tool name.

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?

It gives a chaining hint ('Pair with /sun-times to find current phase'), which implies the required workflow context. But it never states when to choose this over related wellness or moon-phase tools, nor any exclusion conditions, so usage is only partially guided.

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