Update a transaction

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

Annotations declare the mutation safety profile (destructive, idempotent, open-world), so the bar is lower, yet the description adds genuinely non-obvious behavior: partial-update semantics ('only the fields you pass are touched'), null-as-clear, and that server-side rules may rewrite a value on write so the response must be trusted over the request. That last point is exactly the kind of trait annotations cannot express.

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?

Four short sentences, front-loaded with the mutable field list, then the partial-update rule, the unit convention, and the return/rewrite caveat. Nothing is redundant and each sentence carries distinct information.

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?

No output schema exists, but the description compensates by explaining the return value ('returns the transaction as stored afterwards') and warning that rules may rewrite values, which is the key thing an agent needs before trusting its own input. Combined with annotations covering destructiveness and idempotency, nothing material is missing for a 7-parameter mutation 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 100%, so each parameter is already documented, including null-to-clear and cents semantics. The description reinforces the null-clearing rule across category, payee, and note and restates 'Amounts are integer cents,' but adds no syntax or format detail beyond the schema; baseline 3 applies.

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 (Change) and resource (a transaction) and enumerates exactly which fields are mutable (category, payee, notes, cleared flag, date, amount). It also positions itself against siblings by declaring 'The main tool for recategorizing during cleanup,' which lets an agent distinguish it from rule-authoring or note tools.

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 ('the main tool for recategorizing during cleanup') and an operational rule for clearing values via null. It does not, however, name an explicit alternative or state when NOT to use it (e.g. use update_note for bulk note edits, or apply_rule_actions to recategorize many transactions).

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