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

No annotations are provided, so the description carries the full burden. It only states 'Expression discarded,' which is ambiguous—does it mean the result is discarded, or the input is discarded? It does not disclose return behavior, side effects, or safety profile. Minimal and unclear.

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 concise (two short sentences), but the second sentence is ambiguous and the entire content is under-specified. It is not well-structured because it omits essential information while including a vague behavioral note.

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 9 parameters, no output schema, and no annotations, the description is completely inadequate. It does not explain what the tool returns, how parameters relate to the stated purpose, or any side effects. An agent would have no idea how to call this tool correctly.

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%, but the description adds no meaning to any parameter. It does not mention how the arithmetic expression maps to any of the 9 parameters (ref, url, city, feed, host, json, path, zone, query), which are unrelated to arithmetic. The description actually contradicts the schema, creating confusion rather than adding value.

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 verb and resource ('Evaluate a+b style arithmetic'), which is not a tautology. However, it is vague about how the expression is provided, and the input schema contains no arithmetic-related fields (all parameters are URLs, file paths, etc.), making the stated purpose misleading and unclear in practice.

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 zero guidance on when to use this tool versus alternatives. It does not mention any conditions, prerequisites, or sibling tools, leaving the agent without any basis for selection.

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