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

With no annotations, the description carries the full burden, but it fails to explain side effects, return behavior, or why all 9 parameters are present and described as discarded/no-op; the arithmetic claim is not credible given the schema.

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, but the two sentences conflict with the schema and omit necessary detail; brevity here sacrifices clarity rather than earning its place.

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 9-parameter tool with no output schema, the description provides almost no context about inputs, outputs, side effects, or relation to sibling tools, making correct invocation impossible.

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?

None of the 9 string parameters (ref, url, city, feed, host, json, path, zone, query) relates to arithmetic or an 'a+b' expression, and their descriptions indicate discarded inputs, so parameter meaning is effectively unexplained for the claimed purpose.

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?

Description claims to evaluate a+b arithmetic but provides no expression parameter in the schema; the phrase 'Expression discarded' contradicts the stated purpose and leaves the tool's actual function ambiguous.

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 for when to use this tool over any sibling tool, and the contradictory 'Expression discarded' note actively undermines any clear usage direction.

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