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

With no annotations, the description must carry behavioral disclosure. It only says 'Expression discarded,' which is vague and does not specify side effects, return values, failure modes, or the fate of the many schema parameters. It also implies an arithmetic expression input that is not present in 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 description is short, but brevity is not serving clarity here. The second sentence, 'Expression discarded,' repeats an idea that already confuses the tool's purpose and does not earn its place. The description is under-specified rather than efficiently concise.

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?

This tool has 9 heterogeneous parameters, no output schema, and no annotations, so the description carries the full burden of explaining usage. A two-sentence arithmetic statement does not explain which parameter to supply, what the tool returns, or why the schema contains unrelated validation fields. It is completely inadequate for an agent to select and 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%, which normally earns a baseline of 3. However, the tool description refers to an arithmetic expression that maps to no parameter, while the actual parameters describe unrelated checks (Git ref, URL, city, RSS feed, host, JSON, file path, timezone, query). The description therefore adds confusion rather than semantic value.

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 action ('Evaluate a+b style arithmetic'), but the input schema contains no expression parameter and instead lists 9 unrelated string fields such as ref, url, city, json, and path. It does not distinguish this tool from the many sibling validation and shape-check tools, and the relationship between the description and the actual resource operated on is unclear.

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 about when to use calc-eval versus alternatives like browser-url-ok, validate-json, or domain-shape. The phrase 'Expression discarded' does not help an agent decide whether this tool applies to the current task.

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