Accounts — List

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

Annotations already declare the read-only, non-destructive profile, and the description adds substantial non-obvious behavior: balances are in milliunits (1000 = $1.00), and last_reconciled_at is read-only everywhere in this API — reconciling via this server will not move it. The delta-sync mechanics are also explained. This is exactly the kind of context annotations cannot carry.

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?

Front-loaded with the [READ] tag and the core purpose, and most sentences earn their place. The reconciliation point sprawls across three sentences ("marking transactions reconciled does not move it... Only reconciling in the YNAB app does...") that restate the same fact and could be tightened.

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 described, and the description covers the key behavioral traits (units, reconciliation, delta sync) plus an alternative tool. The only real gap is the undocumented plan_id, which is minor for a two-parameter read 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 description coverage is 0%, so the description must compensate and only partially does. last_knowledge_of_server is explained well (it is "the server_knowledge value any earlier response returned"), but plan_id gets no explanation at all, leaving half the parameters undocumented in both schema and description.

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 with scope: "List all accounts for a plan." This distinguishes it from the sibling accounts_get (single account) and from the various transactions_*/categories_* listers without opening any 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?

Gives clear usage context for delta sync ("pass last_knowledge_of_server ... and YNAB sends only what changed since") and names changes_since as the cross-resource alternative for categories/months/transactions. It never explicitly states when to choose accounts_list over the sibling accounts_get, so it stops short of full when/when-not coverage.

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