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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered. The description usefully adds an explicit auth requirement (attachments:write scope), but it is silent on whether omitted fields are preserved or cleared — the critical behavior for an 11-field mutation with destructiveHint=true.

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?

Two short sentences, front-loaded with the action and its identifier. Nothing is wasted, though the second sentence is purely a permission note with no additional operational detail.

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?

With 11 parameters (all optional but id), no output schema, and a destructive annotation, the description should clarify update semantics — partial merge vs. replace, and whether relation FK fields can be reassigned. It covers the auth requirement but leaves those operational questions open.

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 every parameter (id, file_url, file_name, file_size, file_type, description, uploaded_by, and the four entity FK ids) is already documented. The description contributes nothing beyond what the schema provides, so baseline 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?

States a clear verb+resource ('Update an attachment by ID'), which is enough for an agent to know what it does. However, it does not differentiate from the many sibling update_* tools or from bulk_update, and 'update' remains ambiguous about partial vs. full replacement.

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?

Provides no when-to-use guidance, no conditions under which to prefer it over bulk_update or update_* siblings, and no prerequisites beyond the scope mention. Scoping is a permission note, not usage guidance.

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