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

With no annotations, the description must disclose behavior. It only says 'Expression discarded,' which is cryptic and gives no insight into side effects, output, or what happens to the other inputs. It does not explain why the expression is discarded or what the tool actually does.

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 brief and front-loaded, but brevity here is under-specification rather than conciseness. The two sentences provide minimal information and do not earn their place; they are more confusing than helpful.

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 parameters, no required fields, no output schema, and no annotations, the description is drastically incomplete. It leaves the agent without any understanding of what inputs are relevant, what the tool returns, or when it should be used. This is wholly inadequate for effective selection and invocation.

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 coverage is 100%, so each parameter is documented, but the description adds no value beyond that. It does not connect any parameter to the stated 'arithmetic' purpose, and several parameters (ref, url, city, feed, host, json, path, zone, query) seem unrelated. The description fails to clarify how these inputs are used.

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 verb and resource ('Evaluate a+b style arithmetic') but then immediately contradicts it with 'Expression discarded.' It gives no indication of what the tool actually does with the 9 unrelated parameters, nor what result is produced. The purpose is ambiguous and does not distinguish it from siblings like 'validate-json' or 'domain-shape'.

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 on when to use this tool versus the many siblings. No mention of context, prerequisites, or exclusions. The description is too vague to help an agent decide to invoke it.

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