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 covered; the description still adds the cost/free framing and, more importantly, the null selectionVersion semantics as a legitimate first-selection claim. That is genuine behavioral context beyond the structured fields. It does not say what happens when no actor has ever been selected (error vs null), which is the remaining gap.

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 what is read, then the cost posture, then the one non-obvious edge case. Nothing is padded and no sentence repeats the title or schema.

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 zero-parameter read with no output schema, the description covers what is returned (star plus selectionVersion) and how to handle a null version. The only missing piece an agent might need is the behavior when no selection exists at all, but otherwise it is sufficient to invoke correctly.

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?

The tool takes zero parameters, so the baseline is 4. The description mentions selectionVersion, which is a returned value meant to be threaded into a later call rather than an input here — useful but slightly ambiguous about where it gets passed.

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 and resource: 'Read the currently selected star and its selectionVersion', which tells an agent exactly what comes back. It does not explicitly contrast with siblings such as soclo_actors_list or soclo_actors_select, so the reader must infer that this returns only the active selection rather than a collection.

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?

'Free; changes nothing and charges nothing' gives a reason to prefer this over costlier calls, but there is no explicit statement of when to use it versus soclo_actors_list or soclo_actors_select. Usage is only implied: fetch the current selection, likely before calling select.

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