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

Beyond the idempotentHint annotation, the description discloses specific side effects: attaching Whenna's encrypted video room and automatically adding the room link to everyone's calendar. It also notes the creator_key requirement and the mutual exclusivity of place and video room. No contradiction with the annotation.

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?

The description is two sentences, front-loaded with the core action. Every clause adds value: the location option, the video_call option, its calendar side effect, mutual exclusivity, and the auth requirement. No filler or repetition.

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 simple setter with 4 parameters and no output schema, the description covers the main behavior, the two modes, and the auth requirement. It does not mention that omitting both location and video_call is likely invalid, but the schema's optionality makes that a minor gap. Overall, it is sufficiently complete for the tool's 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 covers location and video_call with descriptions, and the description adds extra meaning about video_call's behavior and the exclusivity relationship. However, id and creator_key have no schema descriptions nor are they explained in the tool description beyond 'requires creator_key', leaving their purpose ambiguous.

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 opens with 'Set where the group meets', a specific verb+resource that clearly states the tool's function. It further distinguishes the two modes (place name or video_call) and signals exclusivity, which differentiates it from sibling tools like whenna_best_times or whenna_lock_time that address other aspects.

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 description provides clear context: use this tool to set the group's meeting location. It explains the two options and the required creator_key, but does not explicitly state when to prefer this over sibling tools or exclude cases. The mutual exclusivity note is a useful intra-tool guideline.

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