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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so safety is covered. The description adds genuinely useful behavioral context beyond that: the data is refreshed daily from provider endpoints, and the response includes output price, quantization and 1-day uptime. Freshness cadence and return composition are exactly the kind of detail annotations cannot express.

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?

One dense sentence with zero filler, front-loading the resource and sort order before the secondary return fields. Every clause earns its place and nothing is repeated from the schema or annotations.

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 one-parameter read tool with no output schema, the description does the heavy lifting by enumerating the returned fields (input/output price, quantization, uptime) and the refresh cadence, which compensates for the absent output schema. It is essentially complete, with only the when-to-use gap remaining.

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?

There is a single parameter with 100% schema description coverage ('Model slug or name'), so the schema carries the semantics. The description mentions 'a model' but adds no format, matching, or validation guidance beyond the schema, which is the expected baseline here.

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?

States the resource (all providers serving a model) and the ordering criterion (input price per 1M tokens), which is specific enough to act on. It reads as a full listing sorted by price rather than a single 'cheapest' pick, a mild mismatch with the name/title, but the scope is unambiguous. It does not differentiate itself from siblings like compare_models or get_model.

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 statement of when to use this tool versus the alternatives (compare_models, get_model, search_models), nor any prerequisite or exclusion. The agent must infer that this is the price-comparison lookup from the name alone.

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