ListCategories

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is fully covered by structured data. The description adds one real behavioral trait beyond that: the amounts returned are scoped to the current month and goals are included only 'if any'. No pagination, ordering, or hidden-category default behavior is described, though the hidden flag is documented in the schema.

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?

Two sentences, zero filler. The capability and its return shape are front-loaded, and the sibling redirect is a compact trailing sentence.

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?

An output schema exists, so return values need not be enumerated, and the description still summarizes them usefully. For a read-only, zero-required-parameter list tool with full schema coverage, this is essentially complete; only minor scope questions (ordering, pagination) remain.

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% for both parameters, including the 'last-used' default and the ListPlans cross-reference, so the schema does the heavy lifting. The description adds no parameter-level detail beyond implying the current-month scope; baseline 3 is appropriate.

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?

States a specific verb (List) plus the exact resources (category groups and categories) and even the payload shape: assigned, activity and available amounts for the current month plus goal. This distinguishes it from Ynab_GetCategory (single category) and Ynab_GetMonth (monthly aggregates) without the agent opening either schema.

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?

Explicitly routes one alternative case: 'Use GetMonth for amounts in a different month.' That is a genuine when-to-use rule. It does not, however, address when to prefer this over GetCategory or how it relates to ListMonths, so it stops short of full alternative coverage.

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