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

Annotations declare a non-read-only, idempotent, non-destructive mutation, so the safety profile is partly covered. The description adds that the key originates from list_bills, but does not state whether the change is reversible (undismiss_bill exists), what happens to the payment record, or any effect on budgets. Modest added value, no contradiction.

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?

The first sentence is well front-loaded, but the following two sentences about integer minor units and YYYY-MM-DD/YYYY-MM date conventions do not apply to a tool with only a 'key' parameter. Roughly two-thirds of the description is irrelevant boilerplate, diluting the useful 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?

No output schema exists, so the description should explain the effect of the operation, but it stops at identifying the key source. For an idempotent mutation it omits reversibility, side effects, and prerequisite context. Adequate to invoke, incomplete for understanding consequences.

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 sole parameter 'key' has 0% schema description coverage, so the description must carry the burden. It does add that the key comes from list_bills, which is useful, but then spends its length on amount units and date formats that are irrelevant to this tool's single string parameter. Format expectations for the key itself remain undefined.

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 action (marking a found regular payment as not-a-bill) and identifies the resource via the key from list_bills. The sibling undismiss_bill provides the inverse, but the description never names or differentiates against it, and the title 'Not a bill' is cryptic. Purpose is clear enough to act on 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?

Points the agent at list_bills as the source of the key, which implies the workflow, but gives no explicit when-to-use, when-not-to-use, or alternative (e.g. undismiss_bill is never mentioned). Usage is inferred rather than stated.

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