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

With no annotations, the description carries the full burden. It discloses that the tool computes a ratio from two inputs and presents the result as a percentage. For a pure calculator, this covers the key behavioral aspects, though it does not mention edge cases like division by zero or handling of non-numeric inputs.

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 a single, tightly packed sentence that front-loads the formula and immediately names the required inputs. There is no filler or repetition, and the structure is easy to scan.

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 simple calculator with no output schema, the description provides the formula, inputs, and output format (as a percentage). It stops just short of fully complete because it does not clarify the numeric representation (e.g., '7.5' vs '0.075') or explicitly confirm input formats, leaving minor ambiguity.

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 input schema is empty, so the description's explicit mention of 'noi and value' is the only documentation of parameters. It adds essential meaning by naming the inputs and defining 'value' as property value, but it does not specify types or units, which keeps it slightly below 5.

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 a specific verb ('Calculate'), a specific resource ('capitalization rate for real estate'), and the exact formula (NOI divided by property value). This clearly distinguishes it from the many sibling calculation tools and leaves no doubt about its 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?

The phrase 'for real estate' gives clear context and implies use when a cap rate is needed. It does not explicitly name alternatives or exclusion criteria, but the formula and domain make the appropriate use case obvious among the broader finance/calculator siblings.

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