get_latest

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

With no annotations provided, the description carries the full burden and excels: it reveals that the response is per-parameter independent snapshots, warns about the non-uniform timestamp issue with a concrete example, discloses that values include unit, datum, and provisional/approved status, and explains the effect of max_age_hours. This is far beyond what the schema alone indicates.

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?

Four sentences, each earning its place: the first states the core function, the second disambiguates the trickiest semantic trap, the third tells the agent how to control behavior, and the fourth describes the output envelope. The most critical caveat is front-loaded, and there is zero redundancy.

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 relatively simple three-parameter tool with no output schema or annotations, the description covers the key behavior dimensions: what values mean, how freshness is handled, and what extra fields come back. It could be more complete on what 'location' and 'identifier' mean and what happens if a parameter is not found, but those are minor for the described use case.

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 only 33% (only 'parameters' has a schema description), so the description must compensate. It meaningfully clarifies max_age_hours ('drop the stale ones') and implies 'identifier' maps to a location, but it never elaborates on the 'identifier' parameter format or what codes 'parameters' takes beyond a passing example in the schema. It's adequate but leaves the two most important parameters under-specified in prose.

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?

Uses a specific verb ('returns'), names the resource ('the most recent value the service holds for each parameter at a location'), and immediately distinguishes itself from a sibling concept ('Latest is not the same as current'), which clearly differentiates it from tools like get_series or get_model_forecast. The opening sentence alone fully answers what the tool does and scopes it to location/parameter.

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?

Provides clear context on when to use the tool (when the latest per-parameter values are needed, not an aligned current-time view) and hints at when to use alternatives by warning that values can be non-contemporaneous ('a discharge from this morning beside a turbidity from years ago'). It names the 'max_age_hours' mechanism for handling staleness, which directs the agent toward appropriate invocation. However, it doesn't explicitly name an alternative sibling tool or give an explicit 'don't use if...' condition.

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