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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds substantially more than the structured fields: rate limits and cost model, the mandatory account (API key or OAuth) requirement, and the 10 MB input ceiling. These are exactly the operational facts an agent needs before invoking and are not derivable from the annotations.

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-loaded with the purpose and supported formats, then the per-format field breakdown, then the cost/auth rules. It is dense and the long field enumeration is somewhat list-like, but every sentence carries actionable information and nothing is padding.

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?

Covers formats, accepted input forms, size limit, quota/pricing, and authentication, which is complete for a read-only parsing tool. An output schema exists, so the extra field enumeration is redundant but harmless; nothing an agent needs to call it correctly 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 description coverage is 100%, so the baseline is 3. The description adds only marginal parameter meaning — that a ZIP containing multiple XML files may be supplied (relevant to file_base64) and the 10 MB limit — which the schema already documents, so no credit above the baseline is earned.

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 (liest/parses) plus the exact resource family (camt.052/.053/.054/.086 fee statements) and the output (strukturiertes JSON). It implicitly distinguishes itself from the sibling validate_bank_statement by describing extraction into structured data including ZIP batches, so an agent can tell what this tool does versus validation.

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?

Clear operational context: which message versions are supported, batch-via-ZIP support, the free quota (5 calls/month/account), the payments subscription removing the limit, and the credit cost per extra call. However it never names the closest alternative (validate_bank_statement) nor states when to prefer one over the other, so the routing guidance is implied rather than explicit.

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