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

With no annotations supplied, the description must carry the behavioral burden, and it does disclose two useful traits the schema does not: the data source (Met Eireann) and that values are live observations rather than forecasts. It says nothing about invalid-station failure behavior, update cadence, coverage limits, or returned fields, so the safety and behavior profile remains thin for a tool with zero annotation coverage.

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?

One front-loaded sentence with no filler; every element (live, Irish, Met Eireann, observations, named station) carries information. Nothing is repeated from the schema and nothing is padded.

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 single-parameter lookup with full schema documentation and no output schema, the description covers source, freshness, and geographic scope adequately. A short note on what happens with an unknown station slug, or that these are station-based point observations rather than area forecasts, would close the remaining gap.

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%: the single station parameter already documents the slug format, enumerates valid values, and notes the athenry default. The description only adds that the station is "named", which is no meaning beyond the schema, so the baseline 3 for high-coverage schemas 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?

States a specific verb+resource: "Live Irish weather observations from Met Eireann" for a "named station". The words "Irish" and "observations" implicitly separate it from generic siblings like get_weather, weather, forecast and get_forecast, but no sibling is named outright, so the differentiation is inferred rather than asserted.

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?

"Live ... observations" implies current conditions rather than a forecast, which is the key usage distinction against the forecast/get_forecast siblings, and "Irish" / "Met Eireann" narrows scope to Irish stations. However, there is no explicit when-to-use or when-not-to-use statement and no alternative tool is named, leaving the routing decision to inference in a crowded weather-tool namespace.

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