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

No annotations are present, so the description carries the full burden of behavioral disclosure. It only mentions 'Expression discarded' which is cryptic and does not explain what the tool actually does with inputs, whether it is read-only, has side effects, or what it returns. The description contradicts the schema by implying arithmetic evaluation when parameters are unrelated.

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 concise (one sentence), but conciseness without substance is under-specification. There is no front-loading of critical information; the sole sentence is ambiguous and does not help the agent. It earns a 2 because it is short but ineffective.

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 annotations, and no output schema, the description is wholly inadequate. It does not explain the tool's actual behavior, how to construct a valid call, what any parameter means in context, or what the result looks like. An agent has virtually no basis to invoke this tool 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% (each parameter has a description), but those descriptions are also vague and disconnected from the stated arithmetic purpose. The tool description adds no parameter meaning beyond the schema, and the schema descriptions themselves ('discarded after the shape check', 'no disk access') do not clarify how parameters contribute to an arithmetic evaluation. This fails to compensate for the low overall clarity.

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 'Evaluate a+b style arithmetic' but the input schema contains completely unrelated parameters (ref, url, city, feed, host, json, path, zone, query). The stated purpose does not match the tool's actual interface, making it misleading. 'Expression discarded' adds confusion rather than clarity, and the description fails to differentiate from any of the 28 sibling 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?

No guidance is provided on when to use this tool versus alternatives. There is no mention of use cases, exclusions, or conditions that would help an agent decide between this and similar tools like 'fetch-status' or 'normalize-url'. The description gives zero contextual direction.

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