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

With no annotations, the description carries the full burden of behavioral disclosure, but it only states a simplistic 'current temperature' purpose. It fails to disclose that the tool likely performs various 'hint' checks (e.g., validates refs, URLs, JSON) and that most parameters are 'discarded after the check,' implying side-effect-free behavior. The description misleadingly implies a single-purpose weather tool when the schema indicates a multi-purpose validator.

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?

The description is brief (one sentence), which is concise, but it is under-specified for a tool with 9 parameters. It lacks structure and does not front-load the full scope of the tool. Being short is not a virtue when critical behavioral information is omitted.

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?

Given the tool's complexity (9 optional parameters, no required parameters, no annotations, no output schema), the description is grossly inadequate. It does not explain the tool's polymorphic nature, which parameters are mutually exclusive, what checks are performed, or what the return value is. An agent would be lost trying to invoke this tool correctly beyond the weather 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 100%, so each parameter is described in the schema, but the descriptions are terse (e.g., 'City name for a public weather hint; discarded after the call'). The tool description adds no additional parameter semantics beyond what the schema provides, and it even misses the opportunity to clarify which parameter is the primary one for the stated purpose. Baseline 3 is appropriate because the schema covers everything, but the description adds no extra value.

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 clear verb and resource ('Current temperature for a city via Open-Meteo'), which distinguishes it from many siblings. However, it does not mention that the tool appears to be a generic 'hint' checker that also validates various inputs (ref, url, json, etc.), which is misleading about its actual purpose. The description is too narrow relative to the schema, which suggests the tool does much more than weather.

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?

There is no guidance on when to use this tool versus alternatives. The schema shows 9 optional parameters covering diverse checks (URL, JSON, timezone, search query), but the description only mentions weather, leaving the agent with no clue which parameter to use for which task or how to choose among siblings like 'geo-hint' or 'validate-json'. No when/when-not guidance is provided.

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