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

No annotations are supplied, so the description carries the full burden, and it discloses almost nothing: no return shape, no number of periods, no units, no handling of invalid site codes, no rate limits. The only behavioral detail is the accepted lang values, which is thin for an annotation-free tool.

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?

Two short sentences with zero filler, and the core purpose is front-loaded before the language note. It is terse to the point of under-specification, but that is a completeness problem rather than a verbosity one.

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 0% schema coverage, the description should explain what comes back (periods, fields, units) and how site_code is sourced. Neither is addressed, so an agent can form an intent but not predict the result.

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 0%, so the description must compensate. It does add real meaning for lang ('en or fr'), which the schema leaves as a bare string with a default, but it only restates site_code as 'by site code' without format, source, or validity rules.

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?

States a specific resource ('daily forecast periods') and the keying mechanism ('by site code'), which cleanly separates it from the sibling get_hourly_forecast and get_current_conditions. It stops short of naming those siblings or the alternative lookup path, but the purpose itself is 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?

There is no when-to-use guidance, no prerequisites, and no reference to search_locations for obtaining a site code. An agent must infer from the name alone that this is the daily (not hourly, not current) variant.

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