9router usage

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds only a list of data categories (requests, tokens, cost, provider list) without behavioral context such as time window, aggregation level, or whether the provider list is restricted. This is minimal value beyond what annotations and the output schema already provide.

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?

At five words, the description is exremely concise and front-loded, but it is a sentence fragment rather than a well-formed description. It is more of a label or tag list than an explanatory sentence, which saps structural clarity even though every word earns its place.

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?

This is a zero-parameter, read-only tool with an output schema, so the overall information burden is low. However, the description does not clarify operational context such as whether this is current usage, historical usage, or per-provider breakdown, and it does not distinguish itself from adjacent nine_* tools, leaving some ambiguity for an agent.

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 input schema has zero parameters and required parameters, so schema description coverage is trivially 100%. Per the rubric, a no-parameter tool receives a baseline of 4, and there is no need for the description to clarify parameter semantics.

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 is a noun phrase listing 'Requests, tokens, cost, provider list', which hints at usage metrics but never states a verb such as 'get' or 'list'. It conveys the general subject area but is vague about the action, and the included 'provider list' could overlap with the sibling nine_providers tool, weakening differentiation.

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?

No usage guidance or alternatives are provided. The description never addresses when to choose nine_usage over nine_status or nine_providers, and an agent has no basis for selecting this tool based on context. This is a complete absence of usage direction.

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