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

Annotations already declare destructiveHint=true, so the agent knows this is a mutation. The description adds what gets changed, but does not go further into consequences like irreversibility, effects on splits/transfers, or approval needs. With annotations already carrying the safety profile, this is adequate but not rich.

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?

Two sentences with no filler. The core scoping distinction is front-loaded in the first clause, and the usage trigger is in the second. Every word earns its place.

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?

For a 4-parameter tool with an output schema and destructive annotation, the description gives strong selection and field-scope guidance. Minor gaps remain around date format and the implied requirement to provide at least one mutable field, but the schema and output schema cover much of the invocation detail.

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 50%, with amount and account_id already documented. The tool description confirms date and account are modifiable, but it does not clarify date format or specify that at least one of date/amount/account_id should be supplied alongside id. It partially compensates for the schema gap, but not fully.

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?

The description uses a specific verb ('Change'), names the exact resources affected (amount, date, account), and explicitly distinguishes itself from update_transaction by noting it covers what that sibling 'deliberately leaves alone.' An agent can immediately tell this apart from update_transaction without opening the 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?

It gives an explicit trigger condition ('Use when the user says the number itself was wrong') and names the alternative tool it should be compared against. This is direct, actionable routing guidance rather than a generic description.

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