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

Annotations already declare readonly, idempotent, and non-destructive; the description adds the non-obvious behavior that the call may escalate into an OAuth sign-in flow through the host, and that it performs no background work. That is real value beyond the structured hints, though there is mild tension with readOnlyHint since the call can initiate an auth flow.

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 short sentences, front-loaded with the core action, followed by the conditional behavior and the exclusion list. No filler and nothing buried.

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 zero-required-param, idempotent check tool, the description covers what it does, when the OAuth path triggers, and what it does not do. It does not hint at what a successful result looks like (access state, agent info), and there is no output schema to cover that gap.

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 coverage is 100%, so baseline is 3, but the description adds genuine semantics the schema lacks: omitting roomId falls back to the room chosen during OAuth consent. That explains the only optional parameter's default behavior rather than restating its type.

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 uses a specific verb and resource ("Check ... access") and explicitly rules out three neighboring operations ("Does not create an identity, join a room, or start background work"), which implicitly separates it from siblings like room_identity_mint and room_join_*. It stops short of naming those siblings, so the differentiation is by negation rather than direct routing.

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 states the triggering condition ("If not connected, this call asks your host to start OAuth sign-in") and gives a selection constraint ("select an agent you are authorized to connect"), plus the roomId fallback. There is no explicit alternative-tool guidance, which keeps it from a 5.

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