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

With no annotations, the description carries the behavioral burden and discloses the delete branch, partial-update semantics, and an important domain restriction around issued invoices. It doesn't disclose permissions or the response shape, so it stops short of a 5.

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?

Three tight sentences, each adding a distinct piece of behavior: edit-or-delete, delete flag usage, and the invoice constraint. No filler and the most important operational detail is front-loaded.

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?

Despite having 10 parameters and no annotations, the description, together with the schema, covers selection, invocation, deletion, partial updates, and a critical constraint. Nothing needed to call this tool correctly is missing.

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 coverage is already 80%, so the baseline is 3. The description adds meaning for `delete`, patch-only-changed-fields behavior, and the invoice-state restriction, but it leaves room for confusion by using 'Hours' when the schema uses `duration` and doesn't cover the few undocumented parameters.

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 the exact action ('Edit or delete') and resource ('one time entry'), and distinguishes it from sibling list/log/timer tools without ambiguity. It is specific enough that an agent can select it 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?

Gives concrete usage rules: use `delete: true` to delete, otherwise send only changed fields, and do not change hours/rate on entries tied to issued invoices. It does not name alternative sibling tools explicitly, but the usage context is clear and actionable.

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