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

Annotations already declare read-only, idempotent, and non-destructive. The description adds valuable behavioral context beyond them: the ~500-day archive cutoff, the 1000-day per-call limit, and the presence of DWD quality flags. It does not discuss auth or rate limits, but those are not central here.

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 four tight sentences, front-loaded with the core resource and variables, then operational constraints, then the station_id pointer. Every sentence earns its place; there is no boilerplate.

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 read-only, no-output-schema retrieval tool, the description covers the returned variables, quality flags, data-source behavior, and call limits. It does not describe the return structure or units, but the variable list and DWD conventions make it complete enough to invoke 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%, so the baseline is 3. The description adds meaning by specifying the station_id source (dwd_stations) and a hard date-range limit (max 1000 days per call), which constrains the to/from parameters. This is useful beyond the schema's examples and defaults.

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 states a specific resource—daily climate observations for one German DWD station—and enumerates the variables returned. It also distinguishes itself from dwd_stations by pointing there for station_id, though it does not explicitly name dwd_latest. This is enough for an agent to identify the tool's function.

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?

It provides a prerequisite (get station_id from dwd_stations) and operational context (archive vs daily update, max 1000 days). It does not explicitly compare itself to dwd_latest, so the choice between near-recent data paths is implied rather than stated. Still, the context is clear enough for most calls.

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