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

With no annotations, the description carries the full burden, and it discloses the single most important behavioral trait: presence is a 5-minute window rather than a durable flag. It omits auth requirements, whether repeated calls extend the window, and error behavior, but for a zero-parameter no-op this is close to sufficient.

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, the action front-loaded and the temporal caveat immediately after. Nothing extraneous.

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-arg tool with no output schema and no annotations, the description covers what it does and its time-bounded effect. Only the extension/refresh semantics of the window are missing, which is a minor 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?

The tool takes no parameters, so there is nothing for the description to disambiguate; baseline 4 applies.

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 and effect: 'Mark yourself present' with a concrete scope ('5-minute presence window'). It is distinguishable from read-only siblings like get_presence, though it doesn't explicitly contrast itself with nearby write tools such as post_message beyond the shared side effect.

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?

Clearly implies the use case (registering presence) and, unusually, tells the agent that posting a message also marks you present, which is effectively an alternative path and may let the agent skip this call. No explicit when-not guidance or prerequisites, but the context is unambiguous.

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