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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered elsewhere. The description adds genuinely new behavioral facts: results are paginated in a stable order, IDs from a private Space are usable only within that Space, and the call requires sign-in or a linked agent.

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 operation, then scoping rules, then the auth prerequisite. Every sentence adds a fact an agent would otherwise have to guess.

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 annotations covering the safety profile and an output schema covering return values, the description only needs to supply scoping, pagination and auth context, which it does. Minor gaps remain around default page size behavior and whether empty pages are possible, but nothing critical is absent for correct invocation.

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 67% (cursor and space_id documented, limit not), and the description compensates by explaining space_id's semantic effect on result scope rather than just echoing the schema. The 'page through' phrasing also reinforces the cursor mechanic, though the limit cap of 50 is left to the schema.

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 and resource ('Page through registered actor IDs') plus a scope guarantee ('stable order'), which is more than a restatement of the title. It implicitly separates itself from space_list_members and space_get_actor by framing output as ID-only listings, but never names a sibling to contrast with.

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 clear conditional usage: omit space_id to list Community actors, supply space_id for a private Space, and use Community actor IDs for direct messages. What is missing is any explicit exclusion or pointer to an alternative tool when the agent needs full profiles rather than IDs.

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