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

The description says 'Expression discarded' which hints at a side-effect-free behavior, but there are no annotations to confirm safety. The schema descriptions mention 'discarded after the shape check', 'no disk access', and 'discarded after the length check', which suggest read-only behavior, but the description itself does not disclose this. The mismatch between the arithmetic description and the schema's actual parameters is a transparency issue.

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 (one sentence), which is concise, but it is under-specified and misleading. The phrase 'Expression discarded' is vague and does not clarify what expression is being discarded. The description does not front-load the actual behavior of the tool, which appears to be a multi-purpose validator based on the schema.

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 9 parameters, no annotations, no output schema, and 29 siblings, the description is severely incomplete. The agent cannot determine what this tool does, when to use it, what it returns, or how the parameters relate to the stated arithmetic purpose. The description fails to provide even the basic context needed for correct invocation.

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%, so the schema documents each parameter's meaning. However, the description says 'Evaluate a+b style arithmetic' but none of the 9 parameters represent an arithmetic expression. The description adds no value in explaining how the parameters relate to the stated purpose, and the agent cannot infer which parameter to use for the arithmetic evaluation.

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 says 'Evaluate a+b style arithmetic' which is a specific verb and resource, but the input schema has 9 unrelated parameters (ref, url, city, feed, host, json, path, zone, query) with no arithmetic expression parameter. This makes the purpose confusing and misleading. The description does not distinguish this from the 29 sibling tools, and the schema contradicts the stated purpose.

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 on when to use this tool versus any of the 29 siblings. The description does not mention any context, prerequisites, or exclusions. The schema's 9 parameters suggest it might be a multi-purpose checker, but the description only mentions arithmetic, leaving the agent with no idea when to invoke it.

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