Philippine weather forecast

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety profile is clear. The description adds the non-obvious behavioral detail that it switches between PAGASA TenDay API and Open-Meteo based on the PAGASA_API_TOKEN environment variable. This is valuable context beyond annotations, though it does not describe output format or data update behavior.

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 two sentences, front-loaded with the main purpose, followed by the API selection note. Every word earns its place, and there is no redundant or vague phrasing. It is an exemplary concise description.

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 simple 2-parameter tool with full schema coverage, an output schema, and strong annotations, the description is nearly complete. It covers the main purpose, the location scope, and the API source behavior. It does not specify units or forecast elements, but these are likely covered by the output schema, and no critical gaps are apparent for an agent to invoke the tool correctly.

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%: both 'days' and 'location' are described in the input schema. The description does not add extra meaning beyond what the schema provides, but it does not need to because the schema is self-sufficient. The description's phrase 'Philippine location' aligns with the schema's 'Municipality, city, or province name' without adding detail.

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 opens with a specific verb+resource+scope: 'Get weather forecast for a Philippine location.' This clearly distinguishes it from sibling tools like get_weather_alerts (alerts) and get_active_typhoons (typhoons). The title 'Philippine weather forecast' reinforces the purpose.

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 usage context by stating it is for weather forecasts in the Philippines, which is clear enough to guide selection. It does not explicitly mention alternatives or when-not-to-use cases, but the clear domain and tool name make the intended use obvious. The note about API choice provides additional context for when the tool might behave differently.

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