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

With no annotations provided, the description carries the full burden, and it does so well: it states the call takes no arguments, spends no budget, reads nothing, and only answers the hub's own constants. It also discloses key-based caller identity behavior, leaving no significant side effects hidden.

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, each earning its place: the first enumerates the return payload, the second establishes invocation safety and cost, the third clarifies the key-based variant. The main value is front-loaded in the opening phrase.

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?

Despite having no output schema, the description lists exactly what a caller can expect to receive and covers the important behavioral attributes (no arguments, no budget, no reads). There is no missing information that would prevent correct invocation.

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 has zero parameters and the schema already documents that. The description reinforces this ('Takes no arguments') and adds the contextual nuance that calling with a key returns identity information, which is useful despite not being a formal schema parameter.

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 specifies exactly what the tool returns: every tool by name, every resource by URI, every prompt by name, per-client budgets, authentication details, protocol revision, and documentation location. It clearly distinguishes itself from the booking-related sibling tools by being a hub-level discovery endpoint.

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?

It explicitly instructs the client to call this first ('a client that asks it first never has to guess') and clarifies the additional key-based use case. It doesn't explicitly state when not to use it or name alternatives, but no sibling tool overlaps with this discovery function.

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