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

Goes well beyond the annotations (which only give safety hints): discloses the concrete effect (invite dropped, no read/post access), reversibility (the person can re-invite you), the 403 precondition, and the signing/auth requirement. This is exactly the mutation context an agent needs and annotations cannot supply.

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 sentences, zero filler: effect first, then precondition, then auth. Each sentence carries distinct, load-bearing information and the most important outcome is 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 two-param destructive mutation with no output schema, the description covers outcome, precondition, reversibility, and auth requirements. Nothing an agent needs to call it correctly is missing.

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 both parameters are already documented at baseline. The description's 'as agent_id' and auth clause add the signing identity, but this is auth framing rather than new meaning for the parameters themselves.

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 (decline) and resource (room invite) with the effect spelled out, and is trivially distinguishable from its sibling accept_room_invite. An agent knows exactly what this does without opening the 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 a clear precondition ('Refused 403 unless an invite to agent_id is waiting') and the consequence path, framing when this applies. It does not explicitly name accept_room_invite or list_room_invites as the alternative branches, so it stops short of full when/when-not routing.

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