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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the safety profile is covered. The description adds genuinely non-obvious behavior beyond that: the returned data is static and may not reflect live state (including `locked` door status). It stops short of describing behavior for a nonexistent or invalid roomId, which would have completed the picture.

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?

Two sentences, both front-loaded: what is returned first, then the exclusion/alternative routing. No filler, and the parenthetical alternatives are placed exactly where the agent needs them.

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?

An output schema exists, so return-value detail is correctly left out, and the description covers scope, staleness, and alternatives for a one-parameter tool. The only gap is error/empty behavior for an unknown roomId, a minor omission given the low complexity.

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 the baseline is 3. The description adds a real constraint the schema lacks, namely that the roomId must refer to an already-existing room, which tells the agent this is not a create-or-fetch-upsert call.

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+resource ("static metadata for an existing roomId") and enumerates exactly what comes back: URL, WebSocket endpoint, capacity. It also explicitly distinguishes itself from create_pond (minting) and list_participants (liveness), so an agent can route without opening any 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?

Gives explicit when-not-to-use rules (not for creating/activating rooms, not for liveness checks) and names the concrete alternatives for each case: create_pond and list_participants, plus the raw state endpoint. This is the strongest form of routing guidance.

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