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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds no behavioral details beyond what the schema and annotations already convey, but it does not contradict them. The mention of an API key parameter is captured in the schema, so the description adds minimal extra behavioral context.

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, well-structured sentence followed by a practical example. It front-loads the core purpose and data fields, and the example adds immediate clarity without unnecessary verbosity. Every word earns its place.

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 read-only, idempotent tool with a fully documented schema, the description is complete enough for an agent to call it correctly. It covers input options (city or coordinates), units, and expected output fields. It does not cover error handling or rate limits, but these are minor for such a simple tool and are not typically required.

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%, with every parameter described in detail. The description adds a concrete usage example that demonstrates both city and coordinates input, plus units selection, which reinforces correct usage. While the schema already explains each parameter, the example makes the intended pattern clearer, slightly exceeding the baseline of 3.

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 purpose: 'Get the current weather for a city or coordinates' and lists the exact data fields returned (temperature, feels like, conditions, humidity, wind speed, cloud cover). The verb 'get' is specific, and the resource is unambiguous. While it doesn't explicitly mention the sibling forecast tool, the word 'current' implies a contrast with future weather, which helps differentiation.

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 provides clear context for what the tool does but does not explicitly state when to use it over alternatives like forecast. It implies usage for current conditions, but does not mention that forecast should be used for future weather. No exclusions or alternative routing are provided, so it's adequate but not explicit.

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