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

'Expression discarded' hints that inputs are not persisted, but this does not explain actual behavior: whether validation occurs, whether network access happens, what is returned, or why the listed parameters are accepted. With no annotations provided, the description carries the full burden and fails to disclose the tool's real behavior.

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 only two short sentences, but brevity here is under-specification, not conciseness. The critical information is not front-loaded in a useful order, and 'a+b style' is a confusing non-standard way to state the tool's scope.

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 9 completely unrelated parameters, no output schema, and no annotations, this description is severely inadequate. It explains none of the parameters, no return value, no failure behavior, and no indication of what distinguishes it from its many siblings. An agent has essentially nothing reliable to go on.

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 adds no meaning about how these nine parameters relate to the tool's purpose. Worse, the description's arithmetic framing actively conflicts with the parameter set (none are arithmetic expressions). The description fails to justify or unify the parameters.

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 verb and resource ('Evaluate a+b style arithmetic') but the input schema contains nine string parameters (ref, url, city, json, zone, query, etc.) that have nothing to do with arithmetic. An agent cannot tell what this tool actually operates on, and none of the sibling tools are referenced for differentiation. The phrase 'Expression discarded' adds confusion rather than clarity.

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 call this tool versus any of the 27 siblings. There is no context for conditions, exclusions, or alternatives. An agent has no basis to choose this over tools with similar-sounding shape-check purposes.

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