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

With no annotations, the description carries the full burden of disclosing side effects and behavior. 'Expression discarded' offers a small hint that inputs are not retained, but the description does not explain return values, errors, side effects, or how the many schema fields are treated beyond their own 'discarded' notes.

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?

Two short sentences with the primary action front-loaded; there is no filler. The conciseness is good, though the content is too sparse to fully compensate for the missing guidance.

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 nine heterogeneous parameters, no annotations, no output schema, and no described return shape, two sentences are wholly inadequate. The agent cannot tell which parameter is the expression, what the output looks like, or what 'discarded' means operationally.

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 provides descriptions for all 9 parameters, the tool description introduces an 'expression' concept that does not exist in the schema and gives no clue how parameters like city, feed, or json relate to 'a+b arithmetic'. This actively complicates parameter understanding instead of adding useful meaning.

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 concrete action ('Evaluate a+b style arithmetic') but does not connect it to any of the nine parameters in the schema, none of which is an arithmetic expression. This makes the tool's actual purpose ambiguous and potentially misleading for an agent trying to select it from the sibling shape/validation tools.

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?

There is no guidance about when to use calc-eval versus any of the sibling tools such as validate-json, domain-shape, or timezone. The description merely says what it evaluates, with no context, exclusions, or alternatives.

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