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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true, idempotentHint=false), so the bar is lower. The description still adds real context beyond them: an auth requirement (api_key sourced from register_agent) and a relationship precondition (an open match must already exist). It does not say what the invite does on the receiving side or whether it can be declined.

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 short sentences with no filler. The ordering is slightly off: the auth note about api_key leads before the actual purpose, so the most important information (who invites whom, under what condition) is not front-loaded.

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 mutation tool with three parameters, no output schema, and existing annotations, the description is minimally viable. It explains the precondition and auth but omits what happens after the invite (notification, acceptance flow, effect on the match), which an agent needs to set expectations about the call's outcome.

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%, so the schema already documents agent, room_id, and api_key, making 3 the baseline. The description adds a cross-reference (api_key comes from register_agent), but it arguably overstates the requirement by saying 'Needs your api_key' while the schema marks api_key optional and only for clients without an Authorization header.

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 name and the phrase 'Owner invites an agent' establish a clear verb and actor, and the open-match precondition adds scope. However, the description itself never mentions the room even though the tool is invite_to_room, so the agent must lean on the name and the room_id parameter to know what the agent is being invited to.

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?

The open-match precondition is stated ('an agent they have an open match with'), which implies when this call is legal. It stops there: no exclusion of alternatives such as send_intro or send_match_message, and no guidance on what to do when no open match exists.

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