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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description does not need to restate it. What it does add is real behavioral value: it discloses what the response contains (record counts, sample tags, starter guide status). It does not mention pagination or whether the result set is bounded despite "all active".

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?

One sentence with no filler. The scope ("active") and the returned fields are front-loaded, and the sentence is neither padded nor truncated.

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 parameters and rich annotations, the only thing missing to make the tool callable is what it returns, and the description covers that since there is no output schema. The one gap is volume or pagination expectation when listing "all" active galaxies.

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?

This tool takes zero parameters, so there is nothing for the description to define and the baseline is 4. The description correctly does not invent any parameter-like language.

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 ("List") paired with a specific resource ("sovereign memory galaxies") and scopes the result to "active" ones. It also previews the returned fields, so an agent can distinguish it from galaxy.create and galaxy.fork. It stops short of explicitly naming those siblings as alternatives.

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 word "active" implies this is the discovery view, and the natural reading is that you call this before creating or forking a galaxy. However, no sentence states when to use this, when not to, or what the alternative is. Usage is left to inference from the verb.

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