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

Adds substantial context beyond the annotations: the side effect that the file is stored among the company's underlag, the base64/15 MB size limit, the required 'upload' permission, and the fact that supplying a bilaga returns its current balance and difference. This is rich behavioral disclosure that annotations alone (readOnly=false, destructive=false) do not provide.

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?

Front-loads the core purpose, then alternatives, then return behavior and constraints. It is dense but every sentence carries information; only slight compactness is lost to the multi-clause sentences.

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 no output schema, the description still explains what is returned (current balance and difference) and covers side effects, size limits and permissions. Nothing an agent needs to invoke it correctly is missing for an 8-param upload tool.

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 only 13%, so the description must compensate, and it partially does by explaining that a bilaga is linked for a given account and month and noting the base64/15 MB constraint. However, parameters such as year, bilaga_type, content_type, and name are left undocumented, so the gap is not fully closed.

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 ('Laddar upp ett underlag för en avstämning') with concrete examples (kontoutdrag, avtal, protokoll) and clearly positions itself against siblings add_voucher_underlag and create_underlag_upload. An agent can distinguish it without opening any schema.

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?

Explicitly says when to use it ('underlag som styrker ett saldo i en avstämning') and when to use alternatives instead: receipts/invoices for a voucher go to add_voucher_underlag, large files go to create_underlag_upload. Routing is fully specified.

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