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

Annotations already declare destructiveHint=true and readOnlyHint=false, so the mutation profile is covered structurally. The description adds one genuine behavioral nuance — that the file extension is preserved on rename — but does not state that the previous name is discarded or what authorization is required.

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?

A single compact sentence with the core action front-loaded. The extension clause earns its place, though the semicolon phrasing is slightly awkward rather than maximally crisp.

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 two-parameter rename with no output schema, the description is minimally adequate, given annotations already convey the destructive nature. It omits any return-value expectation and any identifier semantics, leaving notable gaps for the required attachmentId.

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 0% for both parameters. The clause 'a file keeps its extension' weakly clarifies that `name` is the new name and that the extension is retained, but the required `attachmentId` is left entirely undefined by both schema and description.

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 names a specific verb and resource ('Renames an attachment'), which is unambiguous and distinct from add_attachment and delete_attachment. It stops short of any explicit sibling differentiation, but the operation is clearly identifiable.

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?

There is no statement of when to use this tool versus alternatives, no prerequisites, and no mention of the related rename/update surface (e.g., update_task). Usage must be inferred entirely from the name.

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