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

The description adds only the cryptic note 'Expression discarded.' which vaguely suggests the expression is not stored, but it does not state whether a result is returned, whether the operation is read-only, or any side effects. With no annotations present, the description carries the full burden and falls short.

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 with no filler and the core action is front-loaded. However, 'Expression discarded.' is ambiguous and adds little actionable guidance, so while concise, it is not optimally useful.

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 seven heterogeneous parameters and no output schema, this description is severely incomplete. It fails to specify which parameter holds the expression, what the return value is, and whether the tool is safe to call. The agent cannot reliably invoke this tool from the given text.

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 input schema has complete descriptions for all seven parameters, so schema coverage is high. However, the description references 'a+b style arithmetic' and none of the schema parameters accept an arithmetic expression, creating a significant mismatch. The description adds no mapping between the expression and any parameter.

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 'Evaluate' and a resource 'a+b style arithmetic', which clearly distinguishes it from sibling tools focused on URLs, files, JSON, or time. The resource is concrete and the intended domain is obvious.

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 about when to use this tool versus any alternative. The description does not mention context, prerequisites, or exclusions, leaving the agent without any routing signal among the many sibling validators.

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