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. It mentions the external service, but does not state that only the city parameter is used, that other parameters are ignored, whether network calls are made live, or what happens on failure. Too much is left undisclosed.

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?

A single sentence conveys the core function without filler. The most important information, the tool's purpose and data source, is immediately front-loaded.

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?

The tool has nine optional parameters, no output schema, and no annotations, yet the description only states the basic purpose. It does not explain which parameter to use, how to handle the irrelevant parameters, or what the response looks like, making it insufficient for confident invocation in ambiguous situations.

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 the schema already documents all parameters and their discard behavior. The description adds the key connection between city and temperature, but does not clarify why the other eight unrelated parameters exist or whether they affect the weather lookup.

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 clearly states the tool returns current temperature for a city via Open-Meteo, giving a specific output, resource, and data source. It is distinguishable from siblings like timezone or geo-hint, though it does not explicitly differentiate itself from weather-related alternatives.

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 such as web-fetch or geo-hint. No context, exclusions, or selection criteria are provided, leaving the agent to infer applicability.

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