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

Beyond the annotations (readOnly, idempotent, non-open-world), the description discloses pagination via next_cursor, the SMHI quality flag semantics including the caveat that latest-hour data is not quality-controlled, and a licensing/attribution requirement. These are genuinely useful operational details the annotations do not carry, though nothing is said about rate limits or result size 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?

Front-loaded with purpose and pagination mechanics, then a dense but structured field list. It is long, but with no output schema in play the field documentation is doing necessary work rather than padding.

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 output schema, the description properly compensates by enumerating return fields, units, quality codes, and cursor semantics, plus licensing. It is nearly complete for a read-only list tool; the only real omission is routing guidance relative to weather_history.

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%, so the schema already documents all six parameters, and the description's parameter code list (1 temperature, 4 wind speed, 6 humidity, 7 precipitation) largely restates it. The one added detail is the quality-code meaning, which is output rather than input semantics, so the baseline 3 applies.

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 names the specific resource and its scope ('Current weather per SMHI station') and implies a now-vs-history distinction via the word 'Current'. It does not, however, name its obvious sibling weather_history or otherwise differentiate itself explicitly, leaving that inference to the agent.

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?

Usage is only implied: 'Current' suggests this is the latest-observation tool versus weather_history, but no when-to-use guidance, prerequisites, or alternative tool is stated. An agent must infer the boundary from the sibling name alone.

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