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

With no annotations, the description must carry the burden of explaining effects; 'Expression discarded' is the only behavioral hint and it is unclear whether this tool is read-only, returns a status, or silently does nothing.

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 text is short, but the second sentence ('Expression discarded.') is confusing rather than clarifying; the description is too sparse to be 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?

There is no output schema, no examples, no required parameters, and no explanation of how to supply the expression; the tool is largely unintelligible in context.

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?

All 9 parameters have descriptions, but they are unrelated to arithmetic (Git ref, URL, city, host, JSON, path, timezone, query) and none can plausibly carry the 'a+b' expression. The schema therefore provides no meaningful parameter semantics for 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 says 'Evaluate a+b style arithmetic' but the input schema contains no arithmetic expression parameter; 'Expression discarded' makes the actual purpose even more ambiguous. It does not clarify what output the caller receives.

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 sibling validator or arithmetic tool; there is no mention of prerequisites or expected input format.

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