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

With no annotations, the description must disclose behavior, but it only states the core function. It does not reveal that non-city parameters are discarded, that Open-Meteo is an external API (implying network access), or whether the tool is read-only. While the schema mentions 'discarded after the check' for several parameters, the description fails to summarize this behavior or set expectations for the agent.

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, using just nine words to state the primary purpose. It is front-loaded and free of fluff. However, it sacrifices completeness for brevity, omitting any mention of the additional parameters or usage context.

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 nine optional parameters and no output schema, the description is severely incomplete. It only addresses the 'city' attribute and leaves the agent unaware of the tool's multi-purpose nature, potential side effects, and how to leverage the other input fields. Sibling tools clearly follow a 'hint' pattern, but this description does not explain the full scope.

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 coverage is 100%, so all nine parameters have meaningful descriptions. The description adds no semantic value beyond the schema—it simply names 'city' without elaborating on format or constraints. Per the baseline, a 3 is appropriate because the schema already fully documents each parameter.

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 'Current temperature for a city via Open-Meteo' clearly states the primary function: retrieve a city's current temperature from a specific service. It is specific and verb-oriented, and distinguishes it from siblings like 'geo-hint' or 'timezone'. However, it only covers the 'city' use case while the schema exposes nine parameters, creating ambiguity about the tool's overall scope.

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 or when to use each of the nine parameters. There is no mention of exclusions or context for the non-weather parameters. An agent must infer usage solely from the schema, which is insufficient for decision-making among the large sibling set.

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