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

Annotations are absent, so the description carries the full burden of behavioral disclosure. The description only states the core action and says nothing about side effects, safety, rate limits, or how parameters other than 'city' are handled. The schema hints that many parameters are 'discarded' after checks, but the description does not reveal this, leaving the agent unaware of validation or discard behavior. This is a significant gap for a tool with no annotations.

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 a single sentence, which is concise, but it is under-specified for a tool with nine parameters. It front-loads the purpose but omits crucial context about parameter usage and tool behavior. This is not conciseness but under-specification, as the description fails to earn its place by providing necessary guidance.

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?

With no output schema and no annotations, the description must be self-sufficient. It only mentions the city and temperature, leaving out the return format, error handling, and the role of the other eight parameters. The tool's complexity is high (9 parameters) and the description does not explain which parameters are relevant or how they are used. This is incomplete for an agent to invoke correctly.

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%, with each parameter having a description. The schema already provides meaning, so the baseline is 3. The tool description does not add any parameter semantics beyond the schema; it only mentions 'city' indirectly without naming it. However, the schema itself clearly explains each parameter, including that 'city' is for a weather hint and others are discarded. The description does not compensate for any gaps, so a 3 is appropriate.

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 specific purpose: 'Current temperature for a city via Open-Meteo.' It clearly identifies the action (get current temperature) and the resource (city, via Open-Meteo). However, it does not differentiate from siblings like geo-hint or timezone, and the presence of nine unrelated parameters in the schema creates ambiguity about the actual scope. It is clear enough for a weather lookup but not fully distinct from other tools.

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 implies usage when one needs the current temperature for a city, but it provides no explicit guidance on when not to use it or alternatives. There is no mention of competing tools or conditions that would route to another sibling. The intended use is implied but not stated, leaving the agent to infer the context.

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