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

No annotations are provided, so the description carries the full disclosure burden, and it discloses almost nothing: not how many days, not units, not whether the location must be resolvable, not the response shape. "Multi-day" is the only behavioral hint, which is why this is not a 1.

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?

Three words is concise but the brevity comes from omission rather than efficiency; there is no front-loaded statement of scope, return content, or differentiation. It is under-specified rather than tight.

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?

With no annotations, no output schema, and an open schema (additionalProperties true), the description should clarify what the forecast covers and how it differs from the several weather siblings. None of that is present, leaving an agent unable to choose confidently between forecast and get_forecast.

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 description coverage is 100% for the single city parameter, so the schema already documents the 'City, CC' format. The description adds nothing about the parameter, but the baseline of 3 applies when the schema does the documentation work.

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?

"Multi-day forecast" essentially restates the tool name with a scope qualifier. It signals that multiple days are returned rather than a single current reading, but it does not say what resource is forecast (weather is only inferable from siblings) and does not distinguish it from get_forecast, weather, or get_weather.

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?

There is no when-to-use guidance at all: no statement of when this beats get_forecast or weather, no mention that a city is required, and no exclusions. The agent must guess from the name alone.

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