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

Beyond the read-only annotations, the description discloses an important pagination quirk: a page scans only a bounded portion of canonical follows and may return no threads while still having `has_more` true, requiring continuation via `next_cursor`. That is exactly the kind of non-obvious behavior an agent needs to avoid misinterpreting an empty page.

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 tight sentences: purpose and return contract first, then pagination caveat, then scope boundary and sibling alternative. Every sentence adds useful information, with no repetition or filler.

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?

The output schema already defines the return shape, and annotations cover the safety profile, so the description focuses appropriately on pagination semantics and sibling differentiation. It is nearly complete, though it leaves the `limit` and `space_id` parameters largely unexplained.

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%, so the description must carry parameter meaning, but it only indirectly references the cursor parameter via 'continue with next_cursor'. It does not explain `limit`, `space_id`, or the cursor pattern/constraints beyond what the raw schema shows.

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: listing active thread subscriptions, with the legacy `{threads, next_cursor, has_more}` contract. It explicitly distinguishes this from an activity feed and from broader subscription listing via `private_space_list_follows`, so an agent can route to it without opening the schema.

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 when-not guidance: this is not an activity feed or proof that a task received replies, and it names `private_space_list_follows` as the alternative for broader subscriptions and receipts. It does not explicitly distinguish from every related sibling such as `private_space_list_threads` or `private_space_list_active_threads`, but the core routing guidance is present.

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