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

Annotations already declare readOnly, idempotent, and non-destructive behavior, so the safety profile is covered. The description adds value beyond that: it discloses that empty arguments are valid, that runtime identity is preserved, and that the remote hosted UI supports only standard rooms while encrypted content needs the local plugin — all behavioral context not present in structured fields.

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 compact sentences, front-loaded with the action and placement, followed by capability and then the local/remote constraint. No filler or repetition, though the last sentence packs two distinct constraints together.

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?

No output schema exists, and the description covers behavior, identity handling, and the remote-vs-local limitation reasonably well. The gap is the undocumented parameter set: for a 5-param tool with 20% coverage, an agent still cannot tell what room_id, channel_id, page_id, or message_id do or when to supply them.

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 only 20% (only `connection` is documented) across 5 parameters, so the description carries the burden of compensating — and it does not. It says only that empty arguments are accepted, leaving page_id, room_id, channel_id, and message_id completely 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?

States a specific verb (Open) and resource (Tincan rooms) plus a UI placement detail ('sidebar or beside this conversation'), so an agent knows it is a launch/display action rather than a create or join. It does not explicitly contrast with nearby siblings like rooms_list, room_create, or tincan_snapshot, so differentiation is left partly to inference.

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?

Gives implied context ('accepts empty arguments', 'preserves the authorized runtime's identity') and a meaningful constraint ('encrypted content requires the local plugin'), which hints when this will and won't work. However, it never says when to choose this over room_bootstrap, room_join, or rooms_list, so the routing guidance is incomplete.

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