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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description adds value by disclosing that archived/read-only rooms are included and flagged archived=true, that membership governs visibility, and that there is no active-room switch. These are non-obvious behavioral facts beyond the annotations.

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?

Core purpose is front-loaded in the first sentence, and the archived-room detail is useful. The second sentence is somewhat tangled and partially redundant, restating the membership requirement ('only after membership is granted' vs 'additional rooms require explicit membership'), which slightly dilutes it.

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 whose annotations already declare safety, the description covers scope, membership gating, and archived inclusion. With no output schema, it could say more about the returned list shape or pagination, but the essential facts an agent needs to call it correctly are present.

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 100% and the sole 'connection' parameter is fully documented in the schema. The description adds only a thin hint ('using this same connection'), so the baseline 3 applies since the schema does the heavy lifting.

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 ('List your joined rooms in this workspace and your private memory vault') with additional scope detail about archived rooms. An agent can tell this is the read-side counterpart of room_create/room_join/room_members, though it does not explicitly name or distinguish itself from channels_list.

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?

Usage is implied rather than stated: 'joined rooms' plus the membership prerequisite ('only after membership is granted') tells the agent it returns rooms it already belongs to, not a discovery or search tool. However, it never explicitly names alternatives or says when to prefer this over siblings like channels_list or room_members.

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