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

With no annotations, the description must carry the full burden of behavioral disclosure. It only says 'Expression discarded,' which is ambiguous and does not explain what the tool does with the provided parameters, what side effects occur, or what the return value is. This is inadequate.

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 extremely short, but it is under-specified rather than concise. It omits essential information about the tool's behavior and parameters, making it more confusing than helpful.

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 optional parameters and no output schema, the description is grossly incomplete. It does not explain how parameters are used, what the tool returns, or what 'discarded' means in practice. This is far below the minimum viable standard.

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% coverage for parameter descriptions, the tool description adds no value beyond them. It mentions 'expression' but none of the schema parameters represent an arithmetic expression, so the description does not clarify how the parameters are used or how they relate to the stated purpose.

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 'Evaluate a+b style arithmetic' which gives a basic purpose, but it does not connect to the actual parameters (url, city, json, etc.). The description is vague and does not clarify how the tool operates given the schema, nor does it distinguish from sibling tools like validate-json or fetch-status.

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 alternatives. The description does not mention context, prerequisites, or exclusions, leaving the agent with no basis for tool selection.

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