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

With no annotations, the description must disclose behavioral traits. It mentions 'via Open-Meteo' but does not state that an external API call is made, that it is read-only, or how failures are handled. It also fails to clarify that the other parameters in the schema are ignored, leaving the tool's actual behavior opaque.

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 concise sentence that front-loads the main purpose. However, it omits essential context about parameter usage and behavior, making it under-specified. It is efficient in wording but lacks necessary detail, so it earns a middle score.

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?

Given the tool has 9 parameters, no output schema, and no annotations, the description is incomplete. It does not explain the tool's full behavior, which parameters are actually used, what the output looks like, or any side effects. The description is far too minimal for the complexity implied by the schema.

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?

Although schema coverage is 100%, the tool description adds no meaning beyond the schema. The parameter descriptions in the schema are generic and often unrelated to weather (e.g., 'ref' is 'Git ref name; discarded after the shape check'), and the tool description does not compensate by indicating which parameters are relevant or how they are used. This creates confusion rather than clarity.

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 clear purpose: 'Current temperature for a city via Open-Meteo.' It specifies the action (get current temperature), the resource (city), and the data source. It distinguishes from siblings because no other tool is weather-related. However, it doesn't clarify that only the 'city' parameter is used, given the schema includes many unrelated parameters, which slightly reduces clarity.

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 guidance is provided on when to use this tool versus alternatives. The description doesn't mention that it's specifically for weather queries and not for other purposes. It also doesn't state any exclusions or conditions, leaving the agent to infer the intended use from the tool name alone.

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