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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds the ranking criterion and example model detail, which is useful, but it does not disclose other behavioral aspects like pagination or output format. It adds modest value beyond annotations without contradicting them.

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 a single, front-loaded sentence with no wasted words. It states the core ranking logic and the inclusion of example models efficiently, making it easy to parse quickly.

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?

For a simple read-only tool with one optional parameter, the description gives the primary purpose and hints at the return content (example models). However, it omits any mention of the 'limit' parameter's role or the output structure, and with no output schema, an agent might be uncertain about the exact response shape. The core functionality is clear, but completeness is lacking for a fully self-contained description.

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 description coverage is 0% for the single 'limit' parameter, and the description does not mention it at all. The agent must infer that 'limit' controls the number of returned gateways, which is plausible but not explicitly stated. The description fails to compensate for the schema gap, providing no direct guidance on the parameter's 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 states a specific verb ('ranked') and resource ('gateways'), and clearly differentiates from siblings like compare_model_prices or list_gateways by specifying the ranking criterion (number of distinct free models) and the inclusion of example models. This is sufficient for an agent to identify the tool's purpose.

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 implies usage when one wants gateways ranked by free model count, but it does not explicitly state when to use this tool versus alternatives like list_gateways or suggest_models. There is no exclusion or mention of alternative tools, leaving the routing decision to inference.

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