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

No annotations are present, so the description carries the full burden. 'Expression discarded' discloses that input is not retained, but it does not state return values, error behavior, side effects, or whether evaluation succeeds/fails.

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?

Two short sentences with no filler; the operation is front-loaded and 'Expression discarded' adds a behavioral note without waste. It is concise, though perhaps too sparse given the parameter mismatch.

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?

With nine optional parameters, no output schema, and no annotations, the description leaves too much unresolved: which parameter carries the expression and what the tool returns. An agent cannot reliably call this tool from the definition alone.

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?

Although the schema has 100% description coverage for its nine parameters, none of them is identified as the arithmetic expression, and the description doesn't map 'a+b' to any field. This creates a real invocation gap for the agent.

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 operation (evaluate) on a specific resource (a+b-style arithmetic expression), which is enough to distinguish the tool's core intent. 'Expression discarded' also clarifies the stateless nature, but it doesn't explicitly position it against sibling shape-check 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 on when to use calc-eval versus sibling shape-check/validation tools, and no exclusions or prerequisites. The only hint is the one-sentence purpose, which leaves tool selection entirely to inference.

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