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

With no annotations provided, the description must disclose behavior, but it only says 'Expression discarded' which is meaningless since no expression parameter exists. It doesn't explain side effects, permissions, or what the tool actually does with its input parameters. This is severely insufficient.

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 (two sentences), but brevity is not conciseness here. It lacks any useful information and fails to front-load key details. It reads like a placeholder rather than a purposeful, compact explanation.

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?

Given the tool has 9 parameters with rich schema descriptions and no output schema, the description should explain which parameters are relevant, how they relate, and what the tool returns or checks. It provides none of this, making it completely inadequate for an agent to use 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?

The description adds no meaningful semantics for any of the 9 parameters. It mentions arithmetic but doesn't connect to parameters like URL, city, or query. Even though schema coverage is 100%, the description's mention of arithmetic actively confuses rather than clarifies how parameters are used.

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 'Evaluate a+b style arithmetic' which implies a calculation tool, but none of the 9 input parameters (ref, url, city, feed, host, json, path, zone, query) relate to arithmetic. The purpose is unclear and disconnected from the actual parameters, and it doesn't differentiate from any of the 30 sibling 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?

There is no guidance on when to use this tool versus alternatives. The description gives no context about typical use cases, prerequisites, or scenarios where this tool is preferred over its siblings.

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