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

Annotations already declare readOnlyHint and destructiveHint false; the description adds useful context by stating the operation posts nothing and computes interest 'up to today.' This goes slightly beyond the structured annotations by clarifying time scope and side-effect-free behavior.

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?

A single sentence conveys the operation, the scope of accounts, the temporal boundary, and the non-persistent nature of the action. There is no redundant or filler content.

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?

Given zero parameters, read-only annotations, and an existing output schema, the description covers everything an agent needs to invoke the tool correctly. It also addresses the main question of whether this tool mutates state.

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?

The input schema has zero parameters, so the baseline is 4. The description's mention of 'up to today' explains why no date parameter is needed, and there is nothing else for it to clarify.

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 clearly states the tool 'Shows the interest accrue_interest would post on deposit and savings accounts up to today, without saving anything,' giving a specific verb, resource, scope, and side-effect distinction. It also differentiates it from the sibling accrue_interest by emphasizing this is a non-posting preview.

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?

The description implicitly tells an agent to use this tool when wanting to see what interest would be posted without actually posting it, referencing accrue_interest as the actual posting action. It does not explicitly state exclusions or alternative conditions, but the context is clear enough for selection among siblings.

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