calculate_percentage

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

The annotations indicate readOnlyHint=false, suggesting potential mutation, but the description merely says 'calculate' with no mention of side effects, idempotency, or other behavioral traits. It does not add value beyond the obvious, so a 2 is appropriate.

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, front-loaded sentence with no wasted words. It efficiently conveys the purpose, earning a perfect score for conciseness.

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 a simple calculator tool, the description lacks explanation of output format and does not clarify the nuanced difference between operations. While the schema covers parameter descriptions, the description could provide more context, so a 2 is given.

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?

Input schema description coverage is 100%, so baseline is 3. The description lists the operation types but does not add any meaning beyond the schema's enum descriptions and parameter descriptions. Thus, it meets the baseline without added value.

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 the tool 'Calculate percentages, percentage of a number, or percentage change', which clearly specifies the verb and resource. It effectively distinguishes from sibling tools as there are no other percentage calculators, earning a 4.

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 description provides no guidance on when to use this tool versus alternatives or how to choose among the different operations. The enum in the schema helps but the description lacks any usage context, resulting in a score of 2.

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