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

Annotations only declare readOnlyHint=true, but the description adds real behavioral context: results are ordered by newest activity, include unread and mention counts, and per-account failures are returned as `errors` rather than failing the whole call. That partial-failure disclosure is the kind of non-obvious behavior an agent needs.

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?

A single dense sentence that front-loads the resource and scope, then adds ordering, returned fields, and error behavior with no 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?

For a read-only list tool with one optional parameter and no output schema, the description covers scope, ordering, key returned fields, and error handling. Minor remaining gaps (pagination or result limits) are not critical here.

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?

With one parameter at 100% schema coverage, the schema already documents `accounts` including the omit-for-all semantics. The description's '(or a subset via accounts)' reinforces but does not add new meaning beyond the schema, so baseline 3 applies.

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 gives a specific verb plus resource ('List Chatwork rooms'), enumerates the room types (group chats, direct chats, My Chat), and states the cross-account scope. It does not explicitly contrast with nearby siblings like read_chatwork_room or list_chatwork_room_members, but the listing scope is unambiguous.

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 implies usage ('across ALL connected Chatwork accounts (or a subset via accounts)') and the schema points to list_accounts for labels, but there is no explicit when-to-use versus when-to-use-an-alternative guidance, e.g. reading a single room or searching messages.

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