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

Annotations declare readOnlyHint=true, and the description does not contradict that. It adds valuable behavioral context beyond annotations: pricing per result, a cap, and a suggestion to estimate costs via an endpoint. However, it does not describe the return format or any pagination behavior, which would be helpful. The extra pricing info is a positive addition.

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 reasonably concise and front-loaded with the core purpose ('UNDERSTANDING — The biggest rating movers...'), followed by pricing details. It is not overly long and each sentence adds value, though the pricing section could be seen as slightly tangential. Overall, it is well-structured for quick scanning.

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 tool with two optional parameters and no output schema, the description explains the purpose and provides cost context, but it does not describe what the response contains (e.g., list of movers, fields like provider name, rating change, direction). This is a notable gap since there is no output schema to rely on. It is adequate but incomplete for an agent needing to interpret results.

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 schema covers the 'context' parameter with a detailed description, but the 'limit' parameter only has type, default, min, and max—no textual description. The tool description adds no information about either parameter, so it does not compensate for the 50% schema coverage gap. An agent would need to infer the meaning of 'limit' from constraints alone, which is insufficient.

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 clearly states the tool finds the biggest rating movers (up and down) since the previous scoring build. It includes a specific time context and the notion of 'movers', but it does not explicitly differentiate from sibling tools like find_ratings or get_rating_history. The verb 'find' is implied by the title, and the description uses a category label 'UNDERSTANDING', which adds some context but not strong 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?

There is no guidance on when to use this tool versus alternatives. The description focuses on pricing and plan inclusion but does not mention when to choose it over find_ratings or get_rating_history, nor any exclusion criteria. It does not explain what scenario would lead to selecting this tool over others.

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