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

With no annotations, the description must disclose side effects and behavior, but it only says the expression is discarded. It does not mention return value, permissions, side effects, or how the unrelated schema parameters factor into the operation.

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-loaded, but the second sentence is cryptic and the overall under-specification means brevity is not an asset here. It reads more like a stub than a useful definition.

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 9-parameter tool with no output schema, no annotations, and 27 siblings, this description is far too thin. An agent cannot determine what inputs to provide, what the tool returns, or why it exists alongside the other validators.

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 schema descriptions cover 100% of the parameters, so the baseline is 3, but the tool description does not connect any parameter to the advertised arithmetic evaluation. The absence of an expression parameter while the description says 'a+b style arithmetic' actively confuses parameter semantics.

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 claims a specific purpose, 'Evaluate a+b style arithmetic,' but the input schema exposes no expression or arithmetic parameters—only ref/url/city/feed/host/json/path/query. This mismatch makes the tool's actual purpose ambiguous and does not distinguish it from the many sibling shape/URL validators.

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 for when to use calc-eval instead of a sibling such as validate-json or wiki-title-ok. The phrase 'Expression discarded' hints at a behavior but provides no decision rule or alternative.

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