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

No annotations are present, so the description must carry the full behavioral burden. It discloses only that the expression is discarded, not whether the call mutates anything, requires auth, or returns a result, leaving the agent without a clear side-effect or outcome picture.

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 very short and front-loaded: the first sentence names the operation, and the second adds a behavioral note about input retention. There is no fluff, though the brevity contributes to under-specification elsewhere.

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 parameters, no annotations, and no output schema, a two-sentence description is far from complete. It fails to identify the expression input, expected output, or typical invocation, so an agent cannot confidently call the tool.

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%, which gives a baseline of 3, but the description never maps 'a+b style arithmetic' to any of the nine schema properties; none of ref, url, city, feed, host, json, path, zone, or query is an expression field. The agent cannot tell which parameter to pass as the expression.

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 specific action ('Evaluate') and a specific resource ('a+b style arithmetic'), so an agent can understand what the tool is for. It does not name sibling alternatives, but among the listed shape-checking siblings the arithmetic-evaluation intent is reasonably distinguishable.

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 calc-eval instead of a sibling, no prerequisites, and no exclusions. The phrase 'Expression discarded' hints at behavior, not usage context, so the agent has to guess when this tool is appropriate.

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