Transactions — Match statement

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

Annotations already declare readOnly/non-destructive, so the bar is lower, yet the description adds substantial operational context: exact-amount one-to-one matching, closest-date-first ordering, the reasoning against fuzzy matching, the sign-convention trap that silently produces all-unmatched results, and the cost of two requests. This is well beyond what the annotations convey.

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 marker and purpose, and nearly every sentence carries load (sign trap, tolerance rationale, match order, cost). It is dense and long, though, and a couple of clauses could be tightened without losing meaning.

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, yet the description still helpfully characterizes the three result groups, and it covers the matching semantics and pitfalls that matter for correct invocation. The remaining gap is the undocumented account_id, plan_id, and since_date parameters, which an agent must infer from titles alone.

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 0%, so the description must carry the load. It explains rows (date ISO, amount, optional description), both amounts_in modes with the sign convention, and date_tolerance_days including the 'covers a weekend' rationale. account_id, plan_id, and since_date remain undocumented, so it does not fully compensate.

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+resource: pair bank statement rows against an account's register and label leftovers on each side. The unmatched_on_statement / unmatched_in_ynab framing plus the '[READ]' marker distinguishes it from siblings like transactions_list, reconcile_preview, and triage_unmatched_manual.

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?

Clearly frames the scenario (a bank export that needs pairing with YNAB's register) and gives conditions for its tricky options, e.g. when to use amounts_in='dollars' vs 'milliunits'. It does not explicitly name a sibling alternative or say when not to use this instead of reconcile_preview or triage_unmatched_manual, so it stops short of a 5.

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