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

With no annotations, the description alone must disclose behavior, but it is contradictory and opaque. It mentions evaluating arithmetic and discarding an expression, yet no expression parameter exists. It does not state side effects, permissions, or what happens to the provided parameters, leaving the tool's actual operations unknown.

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 two short sentences but is not concise; it is vague and confusing. The sentence 'Expression discarded' is cryptic, and there is no structure that aids comprehension. It is under-specified rather than efficient.

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's complexity (nine parameters, no required fields, no output schema) and the absence of annotations, the description is entirely insufficient. An agent cannot infer what inputs are appropriate, what the tool returns, or how it fits into the broader toolset. The description provides almost no contextual information.

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?

The description adds no meaning to any of the nine parameters. Although the schema provides per-parameter descriptions, they describe diverse data types (URLs, city names, timezones) that have no connection to the stated arithmetic evaluation. The description fails to link the parameters to the tool's purpose, so an agent cannot determine what values to supply.

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 claims to 'Evaluate a+b style arithmetic', but the input schema contains nine parameters (ref, url, city, feed, host, json, path, zone, query) that are unrelated to arithmetic expressions. There is no expression parameter, and the description does not explain how these parameters map to the stated purpose. This mismatch makes the tool's actual function misleading.

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 provided on when to use this tool versus its siblings. The description lacks any conditions, exclusions, or references to alternative tools. The cryptic note 'Expression discarded' offers no practical direction for an agent deciding to invoke it.

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