hub_agents

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by disclosing the returned fields (names, roles, online, status) and the self-marker convention 'Yours says (you)', which an agent could not infer from structured data.

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 clauses, front-loaded with the returned content and no filler. The self-marker note is appended rather than buried. Slightly terse phrasing ('Yours says (you)') costs a touch of clarity but never wastes a sentence.

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?

With no parameters, no output schema, and read-only annotations, the description carries the burden of describing the return payload — which it does by enumerating the fields and the self-entry marker. A small residual gap is the absence of any note on ordering or whether all members are always included.

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 zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly implies a no-argument call that returns the full roster.

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 states the resource (chat participants) and the fields returned — names, roles, online, status — so an agent knows this is a roster/listing tool. The implicit verb 'who is in the chat' is clear enough, though it never uses an explicit verb like 'list'. It differentiates adequately from siblings like hub_inbox or hub_history, though not explicitly by name.

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?

Usage is only implied: an agent can infer this is the tool to call when it needs to know who is present in the chat. There is no explicit when-to-use statement and no mention of alternatives such as hub_profile or hub_status, which could otherwise be confused with this roster lookup.

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