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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals one useful trait: the expression is discarded, implying no persistence. But it does not state whether the tool returns a computed result, writes anything, or errors on invalid input, leaving the agent without essential behavioral information.

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 this is under-specification rather than genuine conciseness. Every word must earn its place, and here the two clauses omit critical invocation details while leaving a misleading reference to a nonexistent expression parameter.

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 nine parameters, no annotations, and no output schema, so the description is the only source of guidance. It is completely inadequate: it does not map the arithmetic expression to any parameter, does not describe the return value, and gives no indication how this tool fits with the many sibling shape-check tools. An agent cannot reliably invoke it correctly.

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?

Schema description coverage is 100%, so the baseline is 3, but the description actively misleads by referring to an 'expression' that does not appear among the nine schema properties. None of the parameters (ref, url, city, feed, host, json, path, query) is identified as the arithmetic expression, so the agent cannot determine where to put the expression when invoking the tool.

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 operation, 'Evaluate a+b style arithmetic', which distinguishes it from the URL/path/domain shape-check siblings. However, it is vague about what 'evaluate' yields, and the added phrase 'Expression discarded' obscures whether a result is returned. The schema contains no expression parameter, so the stated purpose does not cleanly connect to the tool's actual inputs.

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 context is provided: there is no statement of when to prefer calc-eval over alternatives, no exclusions, and no examples. The only hint is the bare description, which does not say under what conditions an agent should invoke this tool.

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