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

The description discloses that the operation stamps entries with an invoice number, causing report and invoice_summary to stop offering them and preventing double billing. This adds meaningful side-effect context beyond the annotations, which only indicate the operation is not read-only and not destructive.

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?

One front-loaded sentence that states the purpose, mechanism, and consequences without padding. Each clause contributes directly to the agent's understanding, and there is no redundant or vague wording.

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?

The description provides the workflow rationale and effects, while the schema supplies all parameter details, including the idempotent skip-and-return behavior for already-billed entries. With no output schema and no safety annotations, this is adequate for correct invocation, though the description could more explicitly mention the two invocation modes (ids vs. project+from+to).

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 all six parameters have descriptive text. The tool description itself adds no parameter-specific meaning beyond what the schema already provides, so the baseline score of 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?

The description uses a specific verb ('stamp') applied to a specific resource ('tracked hours') and explains the downstream effect on report and invoice_summary. This clearly distinguishes it from sibling entry-editing tools by tying it directly to the invoicing workflow.

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 opening phrase 'Close the loop after an invoice is issued' explicitly gives the trigger condition for using this tool. It does not name alternatives or exclusions, but the workflow context is clear enough that an agent can decide when to invoke it.

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