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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuine behavioral context beyond that: the balance is derived from imported transactions and may diverge from the real bank balance if older transactions were never imported. It does not describe the response shape.

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?

Three tight sentences, front-loaded with the definition of the value returned, then the caveat, then the API mapping. Nothing is wasted, though the trailing endpoint reference is marginally redundant given the tool name.

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 read-only getter with full schema coverage and no output schema, the description covers what the value means and its key accuracy caveat. Only the return format (scalar value, currency) is left implicit, which is a minor gap.

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 both parameters are already documented, including the inclusive-to-23:59:59 semantics of date. The description restates the inclusive date behavior but adds no format or syntax beyond the schema; baseline 3 is appropriate.

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 (get) and resource (balance of one check account) plus the exact computation semantics: sum of every transaction sevdesk knows up to and including the given date. It is clearly distinguishable from siblings like list_check_accounts or list_transactions.

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?

Usage is implied by the computation description rather than stated: it is the tool for a point-in-time balance. There is no explicit when-to-use versus alternatives or any stated prerequisites, so it remains minimum viable.

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