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

With no annotations, the description must fully explain behavior. It states inputs are monthly food, vet, insurance, supplies, and setup cost, but it does not disclose how the calculation works (e.g., how first-year vs. lifetime are derived, how lifespanYears is used) or what the output looks like. It also omits the 'other' parameter entirely, leaving a significant behavioral gap.

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 concise at two sentences. The first sentence largely repeats the title, which is slightly redundant, but it adds the active verb 'Add up.' The second sentence delivers useful parameter mapping. The structure is front-loaded with purpose, and each sentence contributes value, though there is minor redundancy.

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?

There is no output schema, so the description should explain return values, but it only says 'see what it really adds up to' without specifying whether it outputs both first-year and lifetime totals or a single total. It also omits the 'other' parameter and does not clarify the role of lifespanYears, leaving the tool under-specified for a 7-parameter calculator.

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 description coverage is 0%, so the description must compensate. It does partially: 'monthly food, vet, insurance, and supplies plus setup cost' assigns meaning to five of seven parameters. However, it does not mention 'other' or explain how 'lifespanYears' should be input, leaving those parameters semantically underdefined. This is a partial but incomplete compensation.

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 clearly states what the tool does: 'Add up the true cost of a pet: first-year and lifetime.' This is a specific verb+resource combination that distinguishes it from sibling pet calculators like pet_food_portion_calculator or puppy_weight_calculator. The scope (first-year and lifetime) is explicit and unique.

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 implies usage when you need to compute total pet costs, but it does not explicitly state when to use this tool versus alternatives, nor does it provide exclusions or mention sibling tools. The phrase 'to see what it really adds up to' suggests a general use case, but specific guidance is absent.

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