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

Annotations only mark readOnlyHint=true. The description adds valuable behavioral context: the exact output fields (temperature in Celsius, humidity, wind speed, plain-language description), the input flexibility (any language, optional country for disambiguation), and the scoping to current conditions. No contradiction with annotations.

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 three sentences, tightly packed. It opens with the core purpose and output, then gives usage examples, then ends with input guidance. Every sentence adds value, with no redundancy or filler.

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 single-parameter tool with an output schema and a read-only annotation, the description is fully adequate. It covers what the tool returns, when to use it, and how to specify the input. The presence of an output schema relieves the description from detailing return structure, and no gaps are apparent.

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 input schema only says 'city' is a string with no description. The description compensates by explaining the city parameter: accepts any language, and country can be added for ambiguous names (e.g., 'Springfield, US'). This adds meaning beyond the bare schema definition.

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's function: 'Current weather conditions for a city, right now.' It lists specific fields (temperature, feels-like, humidity, wind speed) and distinguishes itself from the sibling get_forecast by emphasizing the 'right now' / 'at this moment' 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?

The description explicitly says 'Use for any question about the weather at this moment' and provides concrete example queries. It does not explicitly say 'do not use for forecasts' or name the alternative tool, but the 'right now' language and sibling tool name make the boundary clear.

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