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

No annotations are present, so the description bears the full burden. 'Expression discarded' is a cryptic side-effecting fragment that does not disclose input expectations, return values, mutations, network calls, or error behavior. An agent has no idea what will actually happen on invocation.

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 but severely under-specified. It does not even name which parameter holds the expression, what a legitimate 'a+b style' expression looks like, or whether the invoker should use the tool at all. This is under-specification, not conciseness.

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?

The tool takes 9 optional string parameters and returns no output schema, but the description mentions none of them. It does not specify how the arithmetic is expressed, what is returned when the score succeeds, or what causes an error. This is far too incomplete for an agent to invoke 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 of the 9 parameters has a sentence), which meets the high-coverage baseline of 3. However, the description adds no connection between 'a+b arithmetic' and any of the listed parameters (ref, url, city, feed, host, json, path, zone, query), failing to make the schema coherent.

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 specific verb ('Evaluate') and resource ('a+b style arithmetic'), but no parameter in the schema is an expression, so an agent cannot map the operation to any input. It does not differentiate from the sibling checker/hint 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?

There is absolutely no guidance on when to use this tool versus the 26 siblings, no exclusions, no alternatives, and no preconditions. The 'Expression discarded' clause does not provide selection criteria.

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