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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutating nature is known; the description still adds real value by naming the permission scope and the subscription/plan prerequisite, which annotations never convey. The word 'Irreversible' reinforces permanence, though it doesn't specify what happens to storage/quota or whether errors are returned for missing scope.

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?

Four short sentences, front-loaded with the action and its irreversibility, then id discovery, then prerequisites. There is no redundant or filler 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?

For a one-parameter destructive tool with full schema coverage and annotations covering the safety profile, the definition supplies everything an agent needs: what it destroys, that it cannot be undone, where to get the id, and the plan/scope requirements.

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 100% and the single attachmentId parameter is already documented in the schema, including its uuid format and its source tool. The description only echoes that the id identifies an attachment, so the baseline of 3 is appropriate.

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 verb and resource ('Permanently delete a file attached to a transaction') and implicitly scopes it to attachments rather than transactions, which separates it from delete_transaction and list_transaction_attachments in the sibling list.

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 preconditions (plan must include attachments, finance:delete scope) and points to list_transaction_attachments as the way to obtain an id. It stops short of stating when NOT to use it, e.g. that the parent transaction should be deleted via delete_transaction instead, so it falls just below the explicit when/when-not bar.

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