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

Annotations already cover readOnly/idempotent/non-destructive/openWorld, so the safety profile is known. The description adds value beyond that: data provenance and historical coverage, plus an authority claim that steers tool selection. It does not add operational details like rate limits or pagination, keeping it short of a 5.

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?

Three dense sentences, front-loaded with what the tool returns before the authority/selection guidance. Every sentence earns its place, though the ALL-CAPS emphasis is slightly heavy for the payload.

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?

No output schema exists, but the description enumerates the returned fields (max/min temperature, precipitation, snowfall, snow depth, wind) so an agent knows what comes back. Combined with 100% schema coverage and full annotations, the definition is complete enough, though pagination/limit behavior is left to the schema.

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%, so all 7 parameters including defaults, units, dataset ids, and element codes are documented in the schema. The description adds no syntax or format detail beyond what the schema provides, so the baseline 3 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 pair (daily observed weather) plus the station scope, the returned variables, and the underlying dataset (GHCN-Daily back to the 1800s). An agent can distinguish it from ncei_station_search (finding stations) and ncei_search_datasets without opening either schema.

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?

Gives explicit usage guidance: AUTHORITATIVE for "how hot/wet was it on this date at this place" and PREFER OVER WEB SEARCH for historical US daily values. It names an alternative (web search) but does not state when-not to use it or explicitly route to sibling tools.

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