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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds a concrete behavioral detail beyond that: CDEC's -9999 missing marker is returned as value:null with missing:true, which is useful for interpreting results. It does not mention other edge behaviors like pagination or timezone handling.

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 sentences with no filler. The core purpose is front-loaded, and the second sentence provides a useful data-format note. Every sentence earns its place.

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?

An output schema is present, so return values are covered, and annotations cover the safety profile. However, the description leaves the meaning of start/end parameters unclear, which is a notable gap for a 4-parameter tool with 0% schema description coverage.

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 for parameter meaning. It only references station and sensor; the required 'start' parameter and optional 'end' parameter are not explained at all. The examples hint at dates, but the description itself adds no temporal filtering semantics.

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 (station, sensor) and data type (event-based irregular readings), and 'irregular' differentiates it from regular-interval siblings like daily_data and hourly_data. The action is implied rather than an explicit verb like 'retrieve', so it doesn't earn a 5.

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 phrase 'event-based irregular' implies use for non-regular readings, contrasting with daily/hourly tools, but it never explicitly names alternatives or states when not to use the tool. No exclusions or routing guidance are given.

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