Get top merchants

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

Despite readOnlyHint=true annotation, the description adds meaningful context: it restricts to DEBIT items, defines valueMinor as total spend in minor units, and hints at a time window. These details go beyond what the annotation alone gives, without contradicting it.

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, using two sentences with zero waste. It front-loads the main purpose and then clarifies the spend unit, making it easy to parse quickly.

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?

With no output schema and only two optional parameters, the description covers the core output fields (merchants, spend, visits, category) and relevant details like DEBIT and valueMinor. The only minor gap is the ambiguity of 'window', but overall it is sufficiently complete for selection and invocation.

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 100%, so the baseline is 3. The description does not add extra meaning about the parameters; it only explains valueMinor, which is a return field, not a parameter. Thus no additional value beyond the schema.

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 the tool retrieves the user's most visited merchants by spend, specifying DEBIT items, visit counts, and category. This is a specific verb+resource that distinguishes it from sibling tools like get_merchant_summary or get_spending_breakdown.

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 its use case: when you need top merchants by spend. It provides clear context but does not explicitly mention when not to use it or alternatives, which would push it to a 5. Still, there's enough implied guidance for an agent to select it appropriately.

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