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

With no annotations, the description carries the full behavioral disclosure burden. It adds one behavioral note, 'Expression discarded,' but omits return behavior, side effects, error handling, and what the caller should expect. This is insufficient for a tool with no structured safety hints.

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 short and front-loads the main action, but the second sentence, 'Expression discarded,' is ambiguous and does not clearly earn its place. It is concise but sacrifices essential clarification.

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?

The tool has 9 parameters, no annotations, and no output schema, yet the description provides no parameter mapping, return behavior, or example. An agent cannot reliably select inputs or interpret the result from this definition.

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?

Although the schema has 100% parameter coverage, the description references an 'expression' that does not map to any of the nine schema parameters such as ref, url, json, or query. The agent cannot determine which parameter should contain the arithmetic expression or how these parameters relate to the described operation.

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 clearly states the core action: 'Evaluate a+b style arithmetic.' This is a specific verb and resource, and it distinguishes the tool from sibling shape/URL/file validators. However, it does not explain how the expression is supplied, which prevents a higher score.

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 usage guidance is provided. The description does not state when to use this tool versus any alternative, nor does it give conditions or exclusions. Only an implied use case of arithmetic evaluation exists.

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