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

With no annotations provided, the description carries the full behavioral burden, but it only says 'via Open-Meteo' and does not disclose network dependency, read-only nature, error behavior, units, or that non-city parameters are discarded. The schema hints at discarding, but the description itself does not.

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 one compact sentence with no filler. It front-loads the core function and data source, making it highly concise.

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, a one-sentence description is insufficient. It does not state that city is the meaningful parameter, whether city is required, what temperature unit is returned, or how failures are surfaced, so an agent could invoke it with no arguments or the wrong argument.

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 100%, so the baseline is 3; the schema already documents each parameter. The description adds only that a city is involved and does not clarify which of the nine optional parameters should be populated or that the others are ignored.

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 identifies the tool as returning current temperature for a city and names the data source (Open-Meteo). It lacks an explicit verb like 'Returns', but the intent is unambiguous and distinct from the sibling tools.

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 intended use is implied: choose this tool when you need the current temperature for a city. However, it does not state when not to use it, does not mention alternatives like web-fetch, and does not clarify that only the city parameter matters despite the nine-parameter schema.

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