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. It only says an expression is discarded; it does not state whether the operation is read-only, what output is produced, whether input is persisted, or what the seven schema parameters actually do.

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 and front-loaded with no filler. However, brevity here becomes under-specification: the key statement conflicts with the input schema, so compactness does not translate into clarity.

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 input parameters, no annotations, and no output schema, this description is far too thin. It omits result format, parameter roles, prerequisites, and any indication of what the agent should expect after calling it.

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 every schema parameter has its own description, the tool description fails to tie 'arithmetic evaluation' to any of them and introduces a non-existent 'expression' concept. This is actively misleading rather than helpful, so the high schema coverage does not rescue it.

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 names a concrete action, 'Evaluate a+b style arithmetic', but the input schema exposes no expression parameter—only ref, url, city, feed, host, json, and path. The phrase 'Expression discarded' further muddies what the tool actually computes or returns, so an agent cannot map the stated purpose to any real input.

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: nothing explains when to call calc-eval versus sibling shape-check tools like validate-json, domain-shape, or file-path-ok. The only behavioral statement, 'Expression discarded', is not enough to infer appropriate invocation.

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