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 claims to return temperature for a city, but the input schema lists nine parameters, most of which are marked as 'discarded' or used for unrelated checks (e.g., ref, url, json, path, query). The description does not disclose that these parameters are ignored or that the tool only uses 'city'. This is misleading and contradicts the schema's implied multi-purpose behavior, warranting the lowest score.

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 only one sentence, which is concise, but it is under-specified rather than efficiently structured. It lacks any breakdown of the tool's scope, caveats, or relationship to the extensive parameter list. The brevity does not contribute to clarity; it hides critical information.

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?

For a tool with nine parameters, no required fields, no output schema, and no annotations, this description is severely incomplete. It mentions only 'city' while the schema implies a much broader set of checks. An agent cannot determine how to correctly invoke the tool, what to expect in response, or what the other parameters are for. The description fails to provide the necessary context.

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 each parameter has a description in the schema. The tool description itself adds nothing about parameter usage, but the baseline is 3 because the schema already documents parameters. However, the descriptions in the schema are odd (e.g., 'discarded after the shape check') and do not clarify how they relate to the stated weather purpose, which slightly reduces the value added beyond the schema.

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 action (current temperature) for a specific resource (a city) via a named service (Open-Meteo). This is clear and distinguishes it from unrelated siblings like validate-json or browser-url-ok, but it does not explicitly name any alternative or contrast with a close sibling (e.g., geo-hint). It is not a tautology and provides a definite purpose.

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, nor any mention of prerequisites or exclusions. The description simply states what it does without any context about appropriate use cases, input restrictions, or what the tool is not for.

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