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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is fully covered elsewhere. The description adds the useful behavioral constraint that only *major* phases are returned (skipping intermediate phases) and that results are capped at 12, but says nothing about ordering, return shape, or how defaults behave.

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 front-loaded sentence with no filler; every clause (the phase list, the start date, the 12 cap) carries information. It is compact to the point of being slightly terse, but no sentence 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 simple, fully annotated, zero-required-parameter read tool with complete schema coverage and no output schema, this is nearly complete. The only real gap is the absence of any disambiguation from astronomi_moon, which matters given the dense astronomical sibling set.

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%, so both parameters (count, tanggal) are already documented with types, ranges, and defaults. The description's 'from a start date, up to 12 ahead' merely restates those parameters in prose without adding format details or edge-case behavior, so the baseline of 3 applies.

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 verb ('List') and resource ('next major moon phases') and even enumerates the four qualifying phases (new / first quarter / full / last quarter), so scope is unmistakable. It does not, however, name or contrast itself with the sibling tool astronomi_moon, which an agent could reasonably confuse with a phase-listing tool.

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?

Usage is implied by 'from a start date, up to 12 ahead', which tells the agent this is a forward-looking enumeration rather than a point lookup. There is no explicit when-to-use or when-not-to-use guidance and no reference to the alternative astronomi_moon tool for current-phase lookups.

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