hub_presence

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

With no annotations, the description carries the burden of disclosing behavior. It explains the alive/stale derivation from ttlMin, which is useful. However, it does not explicitly state that this is a read-only operation or mention any side effects, permissions, or caveats like truncation (though truncation is in the schema). The description implies read-only but does not confirm it.

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 concise, consisting of two sentences that efficiently convey the core purpose and a helpful pairing with hub_brief. The second sentence is slightly dense with the em dash and metaphorical language, but every phrase contributes valuable context.

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?

Given the tool's simplicity and full schema coverage, the description provides adequate context: it defines the roster, the alive/stale flag, and how it integrates with hub_brief. It does not detail the output format, but without an output schema, the description's high-level overview is sufficient for this read-only listing tool.

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% for the three parameters, so the schema already documents them fully. The description does not add any parameter-specific meaning; it only mentions ttlMin, which relates to the live/stale concept rather than any input. Thus, the description adds no value beyond the schema, warranting the baseline score.

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 clearly defines the tool as a fleet roster of agents that have called hub_heartbeat, with alive/stale status based on ttlMin. It uses a specific verb+resource construction and distinguishes itself from sibling tools like hub_heartbeat (the act of beating) and hub_brief (queue info).

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: it is for checking who is listening/active, and explicitly pairs with hub_brief's queue section. However, it does not explicitly state when to prefer this over alternatives or mention exclusions, so it stops short of full guidance.

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