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

Annotations already indicate this is a non-read-only, non-idempotent, non-destructive operation. The description adds useful behavioral context beyond annotations: base64 encoding, per-item and per-dispute size caps, and role restrictions. It does not describe the response or error behavior, so it is not 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?

Two tight sentences with no filler. The main purpose is front-loaded, and the critical constraints (base64, size caps, authorized uploaders) follow immediately in the second sentence.

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 simple mutation tool with five flat parameters, no output schema, and existing annotations, this description covers everything essential: what to attach, to which dispute, in what encoding, under what size limits, and with what authorization. No critical operational detail 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 100%, so the baseline is 3. The description adds meaningful value by introducing the per-dispute 200 MB cap, which is not present in the schema, and by reinforcing the per-item cap and base64 encoding requirements. Most parameter details remain in the schema, but the extra constraints help an agent plan payloads correctly.

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 states a specific action, 'Attach an evidence item to an open dispute', with a clear verb and resource. It also includes a precondition ('open dispute') that distinguishes this tool from dispute filing, listing, responding, and withdrawal siblings.

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 description gives clear context: the dispute must be open, and the uploader must be either the filing buyer or the seller-owner. It does not explicitly name alternative tools or state when not to use it, so it stops short of full routing guidance.

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