9router combos

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

The description discloses no behavior beyond what the readOnlyHint annotation already implies. It doesn't say what the tool computes, returns, or affects. Since annotations already cover the read-only safety profile, the description adds no behavioral context.

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 only one sentence, but brevity here is under-specification rather than conciseness. The phrase 'Combos with member models' does not earn its place because it lacks a verb and clear meaning. It is too minimal to support selection or invocation.

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?

Although there are no parameters and an output schema exists, the core operation is still ambiguous. With several similar nine_* sibling tools, an agent has no way to know what a 'combo' is or when to call this tool. The description is not complete enough for confident selection.

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 an empty schema, so there are no parameter semantics for the description to clarify. The model examples in the description provide mild domain context, but parameter semantics are not applicable; baseline for 0 params is 4.

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, 'Combos with member models...', with no verb indicating what the tool does. The title repeats 'combos,' making it nearly tautological. The model examples give a hint of subject matter, but an agent cannot tell whether this lists, creates, or runs combinations.

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?

There is no guidance on when to use this tool versus the many nine_* siblings such as nine_models, nine_chat, or nine_providers. The description does not state a use case, prerequisites, or exclusions, so the agent must guess.

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