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,' but there is no expression parameter, and it doesn't explain side effects, permissions, or what happens to the inputs. It is misleading and incomplete.

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 extremely short (two sentences) but that is under-specification, not conciseness. It front-loads nothing useful and omits critical context about parameters and behavior.

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?

For a tool with 9 parameters, no output schema, and no annotations, the description is drastically incomplete. An agent cannot infer the tool's purpose, correct usage, or expected results. It fails to provide even a basic level of context.

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 schema descriptions cover 100% of parameters, but the tool description adds no unifying meaning—it doesn't explain how these nine disparate parameters relate to arithmetic or to each other. The baseline 3 is not met because the description actively contradicts the schema's apparent purpose, leaving agents unable to map inputs to the tool's function.

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 to 'Evaluate a+b style arithmetic' but the schema has no arithmetic expression parameter; it lists unrelated fields like ref, url, city, and query. This creates a mismatch that confuses rather than clarifies the tool's actual purpose, and it does not differentiate from siblings like normalize-url or fetch-status.

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 any of the 26 sibling tools. No context, no exclusions, no mention of alternatives. The description offers zero help for selection.

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