get_forecast

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

Annotations already indicate readOnlyHint, idempotentHint, and non-destructive behavior. The description goes beyond annotations by specifying units, time resolution, geographic coverage, and error behavior (returns isError: true on out-of-range coordinates or API unavailability). 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 a single dense paragraph that efficiently covers scope, resolution, unique fields, alternatives, units, errors, and coverage. While longer than the ideal two-sentence example, every clause adds necessary context and the structure is logical.

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 complex forecast tool with no output schema, the description provides all essential context: time resolution, unit system, error handling, geographic boundaries, and explicit relationships to sibling tools. It gives the agent enough information to select and 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?

The schema already documents both parameters with ranges (100% coverage), so the description adds limited but valuable semantics: the valid geographic coverage area (Sweden, Norway, etc.) and unit conventions. This supplements the schema without redundancy.

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 returns the full ~10-day weather forecast with every raw SMHI parameter at native resolution. It explicitly distinguishes itself from sibling tools by noting it includes fields not exposed by the others, 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?

The description explicitly tells the agent when to use alternatives: 'Prefer get_current_weather for a single now-reading, get_hourly_forecast for an hour-by-hour view, or get_daily_summary for a multi-day high/low overview' and then states 'use this tool when you need the complete unprocessed dataset.' This provides clear when-to-use and when-not-to-use guidance.

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