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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds the useful auth prerequisite ("currently authorized private Space"), but it says nothing about pagination behavior or result ordering, and the confusing continuation/seen-state sentence adds noise rather than behavioral clarity.

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 sentences, but the second one ("Reply and mention continuations belong to this task; shared seen state does not prove receipt") is confusing and appears unrelated to listing actors, so it does not earn its place. The one genuinely useful constraint is front-loaded in sentence one.

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 needn't be described, but the description still leaves the core concept (what an actor is) undefined and gives no pagination semantics despite the limit/cursor params. For a low-complexity list tool this is under-specified rather than adequately complete.

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 0% for all three parameters, so the description carries the full burden. It only vaguely gestures at space_id via "within one currently authorized private Space" and never mentions limit (max 50) or the cursor format, leaving two of three parameters unexplained in both schema and prose.

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 first sentence names the verb+resource ("list actors") and adds a scope constraint ("within one currently authorized private Space"), but it essentially restates the tool name/title and never explains what an "actor" is. It does nothing to distinguish this from siblings like private_space_list_members, private_space_get_actor, or public_space_list_actors.

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 only usable guidance is the implied precondition that the Space must be "currently authorized". There is no when-to-use/when-not, no mention of alternatives such as private_space_list_members or public_space_list_actors, and the second sentence about reply/mention continuations and "shared seen state" reads as misplaced guidance that does not help select or invoke this listing tool.

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