List direct debits

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context the annotations do not carry: the default result set excludes cancelled mandates, and results can be narrowed by account. It stops short of describing pagination or result limits.

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?

Three tight sentences, no filler, with the core purpose and returned fields front-loaded ahead of the filtering caveats. Efficient, though the field enumeration is a slightly long list for a single 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?

With no output schema, the description compensates by naming the returned fields (originator, reference, status, dates, amount, category), and it covers the default filter and account scoping. The unmentioned 'detail' parameter is the one notable omission for a 3-parameter tool.

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 coverage is 67%; the description reinforces includeCancelled ('set includeCancelled to see cancelled ones') and accountUid, matching their schema descriptions with the added 'by default' nuance. The 'detail' enum parameter (compact/full) has no schema description and is never mentioned in the description, leaving a real gap.

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 and resource ('Lists direct debit mandates'), then disambiguates the concept with a parenthetical gloss ('who can take money by direct debit') and enumerates the fields returned. This clearly separates it from the singular get_direct_debit_mandate and from list_direct_debit_payments without requiring the agent to open 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?

The description gives behavioral guidance on default filtering ('Only LIVE mandates by default') and scoping ('Pass accountUid to restrict to one account'), which tells the agent how to call it. However it never states when to prefer this tool over siblings like get_direct_debit_mandate or list_direct_debit_payments, so the usage guidance is implied rather than explicit.

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