Get weather forecast

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

With no annotations, the description carries the burden and does well: it explains the output format (one entry per day with conditions, temps, rain, wind) and the forecast horizon. It doesn't mention potential limitations or side effects, but for a read-only forecast, no such concerns are expected, so this is acceptable.

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 compact and front-loaded. It uses three sentences to cover purpose, usage examples, and the alternative tool, with no filler. Every sentence contributes value.

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?

The description fully compensates for the missing output schema by summarizing the response structure. It also provides semantic context (daily entries, fields) and clear sibling differentiation. For a simple 2-parameter tool with a rich schema, nothing essential is missing.

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 covers 100% of parameters with detailed descriptions. The tool description adds a little extra context about output entries and the usable day range, but it largely reiterates what the schema already conveys, so it doesn't significantly elevate beyond the schema baseline.

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 ('Look up the daily weather forecast for a city') and scope (1-7 days ahead). It explicitly distinguishes from the sibling tool get_current by directing users there for current conditions, making the purpose unambiguous.

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?

Provides explicit when-to-use guidance with concrete examples ('what tomorrow looks like, whether the weekend will be dry') and names the alternative for real-time conditions ('use get_current instead'). This fully addresses usage context and selection among siblings.

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