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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint, covering the safety profile. The description adds valuable context about the data source, license, auth requirement, and the fields returned, which goes beyond the structured annotations. No contradictions.

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 wasted words. The first sentence states the function and output; the second handles licensing and auth. Everything is front-loaded and essential.

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?

The tool is simple (one parameter, read-only, output schema exists), and the description covers the core elements: what it returns, where the input comes from, and access requirements. It could mention rate limits or data lag, but these are minor given the annotations and schema richness.

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 parameter is fully documented. The description enhances this by specifying that measure_id is a notation returned by ea-hydrology.station_measures, providing important cross-tool context that is not in the schema. This adds meaning beyond the schema alone.

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 uses a specific verb ('Get') and resource ('most recent reading') and names the exact output fields (date, value, quality flag). It explicitly references the measure_id source, distinguishing it from the range-reading sibling. This is a clear, unambiguous statement of what the tool does.

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 description tells the agent that the measure_id must come from ea-hydrology.station_measures, which is a crucial prerequisite. It does not explicitly list alternatives or when-not-to-use, but the 'latest' vs. 'range' sibling names make the intended use case evident.

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