Money movement groups — List

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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower, and the description still adds meaningful non-obvious behavior: groups carry no amount, movements join on money_movement_group_id, and last_knowledge_of_server must be fed the server_knowledge value from a prior response. It does not mention pagination or rate limits, but the delta-sync contract is the important disclosure here.

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 sentences, front-loaded with the read tag and the core action, then the domain model, then the sync mechanics. Every sentence carries information. The closing clause about changes_since is slightly tangential for a list endpoint but earns its place as sibling routing.

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 spelled out, and the description covers the object semantics, the join key, and the incremental-read contract. The gaps are minor: what happens when plan_id is omitted (all plans vs. error) and whether results are paginated are not addressed.

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% and there are no descriptions on either property, so the description must compensate — and it does for the harder parameter, explaining exactly what last_knowledge_of_server expects ('the server_knowledge value any earlier response returned') and why. plan_id is only implied by the phrase 'for a plan', and its null default is never explained.

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 ('List money movement groups for a plan') and then defines the domain object itself: 'A group ties together the movements made in a single action; it carries no amount of its own.' That definition cleanly separates it from money_movements_list and money_movement_groups_list_by_month, which an agent cannot infer from the name alone.

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?

It gives real guidance for the delta-sync path ('pass last_knowledge_of_server ... YNAB sends only what changed since') and names changes_since as the cross-entity alternative. But it never says when to pick this tool over money_movement_groups_list_by_month or money_movements_list, nor whether plan_id is required in practice, leaving the core routing decision implied rather than stated.

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