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

With no annotations, the description carries the full burden of behavioral disclosure. It only says 'via Open-Meteo,' hinting at an external dependency, but does not disclose that most schema parameters are discarded, what the return format is, whether the call is read-only, or any rate limits or error behavior. The schema notes 'discarded' for many parameters, but the main description 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 a single, tightly worded sentence with no redundant content. It front-loads the core function and data source, making it easy to scan. Every word contributes to the agent's understanding.

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 straightforward temperature lookup, the description is sufficient to select the tool, but it leaves gaps: no units, no output format, no mention of the eight non-city parameters or their ignored status. The schema partially fills these gaps, but the overall package relies heavily on the schema for full context.

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 schema already documents each parameter, including 'City name for a public weather hint'. The description adds little beyond the Open-Meteo data source, which is not parameter-specific. It does not meaningfully enrich the meaning of the parameters beyond what is already in the schema.

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 a specific function: returning the current temperature for a city, and identifies the data source (Open-Meteo). This makes the primary purpose easy to identify and distinguishes it from sibling hint tools. However, the schema includes eight additional parameters with no mention in the description, which could confuse an agent about whether the tool serves broader purposes.

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 description implies the tool should be used when a current city temperature is needed, but it gives no explicit guidance on when to prefer it over similar siblings like geo-hint. There are no exclusions, alternatives, or conditions mentioned, leaving usage inference to the agent.

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