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

Adds real behavior beyond the annotations: size and count limits (10 MB, 20 per order), what happens afterwards (bills are parsed and compared to entered consumption, an Energieberater reviews photos), and 'Orders nothing', which reassures the agent this is not a committing action. It does not address what happens on re-upload of the same file despite idempotentHint=false, which is a minor gap.

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 compact sentences: what it does, allowed inputs and limits, downstream processing, and the no-commit guarantee. Front-loaded and free of filler.

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?

Given an output schema and fully described parameters, the description covers the workflow position, limits and downstream effects an agent needs to call it correctly. Only duplicate-upload behavior is unaddressed.

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 each parameter is already documented, including the kind enum values and the base64 size cap. The description reinforces the accepted formats and size but adds no semantics absent from the schema; 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 specific verb and resource ('Uploads a file to a draft order') and immediately enumerates what a file can be (energy bill, Heizkostenabrechnung, photo types). This clearly separates it from siblings like start_order or update_order, which never accept binary content.

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?

Explains the intended context: files attach to a draft order before/around ordering, and photos are usually taken by the customer after the confirmation email. It does not name an alternative tool or state exclusions explicitly, so it stops short of a 5.

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