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

Annotations already declare readOnlyHint and destructiveHint false, and the description reinforces that with 'without changing anything.' It goes beyond annotations by scoping to 'existing transactions' and by disclosing an output behavior ('how many rows are affected'), which is useful for an agent deciding whether to present this as a dry-run.

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 front-load the core purpose and behavior first, then give usage context. There is no filler, and the structure mirrors the natural scan path for an agent evaluating the tool.

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 simple read-only tool with two parameters, the description plus detailed schema covers what the tool does and when to use it. Minor gaps remain around the exact return shape and the unlisted apply_rule dependency, but neither blocks correct invocation.

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%, with ruleId and householdId already well-documented including source hints ('from list_rules') and an omission condition. The description itself adds no parameter-level detail, so the baseline of 3 applies because the schema does the heavy lifting.

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 ('show') with a clear resource ('which existing transactions a rule would touch') and immediately distinguishes itself from an apply operation by adding 'without changing anything.' This cleanly separates it from list_transactions and any rule-modification action.

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 gives explicit use cases: 'check a rule before apply_rule' and 'tell the user how many rows are affected.' However, it does not give when-not guidance or explicitly name alternatives among the listed siblings, and the referenced apply_rule is not present in the sibling-tool list, leaving a minor route-selection gap.

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