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

With no annotations, the description carries full responsibility for disclosing behavior. It only says 'Current temperature' which implies a read-only action, but it doesn't explain that other parameters are discarded or that the tool performs other checks (as hinted by schema descriptions like 'discarded after the shape check'). The description doesn't reveal the multi-purpose nature or any side effects, leaving the agent uncertain about what happens when other parameters are provided.

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 under-specifies the tool's behavior. It lacks structure and doesn't front-load critical disambiguation. It is more under-specified than genuinely concise, as it omits necessary context.

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 has 9 parameters, no output schema, and no annotations, the description is severely incomplete. It doesn't explain the full set of operations, the return format, or how to handle multiple parameters. An agent cannot correctly invoke this tool for anything beyond the trivial city-temperature case, and even that lacks detail like units or API specifics.

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?

While schema coverage is 100%, the description adds no value for parameters beyond mentioning 'city'. It doesn't clarify which parameters are relevant for the weather function or how the others are handled. The description fails to compensate for the confusion caused by the many optional parameters, so it doesn't help the agent decide what to provide.

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 purpose for the weather use case: 'Current temperature for a city via Open-Meteo.' However, the schema includes 9 unrelated parameters (ref, url, feed, host, json, path, zone, query) that suggest the tool is multi-purpose, yet the description only covers one function. This makes the actual scope ambiguous and does not distinguish it from siblings like geo-hint or timezone.

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 provides no guidance on when to use this tool versus alternatives. It doesn't mention that it handles multiple hint types or specify conditions for selecting weather-hint over siblings like geo-hint or timezone. No exclusions or alternative routing is given.

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