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 only mentions weather and does not disclose that the tool also processes URLs, JSON, paths, queries, etc., as shown in the schema. This is misleading—an agent seeing the schema would be confused about the tool's actual behavior, since the description contradicts the apparent multi-purpose nature. The schema descriptions say parameters are 'discarded' or 'checked', implying a more complex tool, but the description fails to convey that.

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, efficient and front-loaded with the main purpose. However, it is too brief given the tool's complexity, omitting crucial information about the other parameters and behaviors. It earns a 4 for brevity but not for completeness.

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?

This tool has 9 parameters, no output schema, and no annotations. The description only covers the city/weather use case, leaving the other eight parameter types unexplained. An agent cannot infer how to use the tool for URL, JSON, timezone, or other inputs. The description is severely inadequate for the tool's actual scope.

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 all parameters have descriptions in the schema. The tool description adds no parameter-specific meaning beyond what the schema already provides. Baseline 3 applies because the schema does the heavy lifting.

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'), with a specific verb and resource. However, it does not mention the other capabilities implied by the input schema (URL normalization, JSON validation, timezone, etc.), so an agent cannot tell that this tool serves multiple functions. It partially distinguishes from siblings but is incomplete.

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?

No guidance is given on when to use this tool versus alternatives like 'geo-hint' or 'web-fetch'. The description does not mention any exclusions, prerequisites, or context for choosing this tool. An agent must rely on the schema and sibling names, which is insufficient.

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