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

No annotations are provided, so the description carries the full disclosure burden. It discloses 'Expression discarded,' but this refers to an arithmetic expression that does not exist in the schema — a phantom behavioral note. It says nothing about what happens to any of the 9 real parameters (e.g., whether they are validated, normalized, or discarded), leaving the tool's actual behavior completely opaque.

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 brief — two short sentences with no wasted words — but brevity here comes at the cost of correctness. It is under-specification rather than good conciseness: it omits how the tool relates to its actual parameters and states a purpose contradicted by the schema. Front-loading an inaccurate claim does not earn conciseness credit.

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 is a 9-parameter tool with no output schema and no annotations, so the description carries full responsibility. It explains none of the real parameters, introduces a task (arithmetic) not represented in the schema, and gives the agent no way to invoke the tool correctly. This is completely inadequate for a tool of this parameter count.

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 coverage is 100%, which normally earns a baseline of 3, but the description actively harms parameter understanding by introducing an 'a+b' arithmetic concept entirely absent from the schema. An agent would be unable to map the described task onto any of the 9 actual parameters. The description adds no meaning to the schema's parameters and instead inserts a phantom one, which is worse than adding nothing.

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 claims the tool evaluates 'a+b style arithmetic,' which is a clear verb+resource on its face. However, the input schema contains no arithmetic or expression parameter whatsoever — the 9 actual parameters (ref, url, city, feed, host, json, path, zone, query) are about URLs, timezones, JSON validation, and file paths. The description's stated purpose does not match the schema it governs, making it misleading for an agent trying to figure out what the tool actually operates on.

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 its 26 siblings. The description doesn't reference alternatives, exclusions, or conditions. Worse, since the stated purpose (arithmetic) contradicts the actual parameters, an agent gets no usable context about when this tool would be the right choice among tools like normalize-url, validate-json, or timezone.

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