Look Up Vouchers by Number

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

Annotations already declare readOnlyHint=true and idempotentHint=true, but the description adds valuable behavioral context by disclosing the API's 400 error when voucherNumber is missing and noting that summary fields like contactName and openAmount are absent from this endpoint. This goes beyond the structured 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?

The description is three sentences long, front-loaded with the core purpose, then providing crucial usage and behavioral details. No fluff or redundant repetition; every sentence earns its place.

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 lookup tool, the description covers the essential information: when to use, critical parameter requirement, error behavior, and what fields are not returned. Combined with the strong annotations and full schema coverage, it is complete and actionable for an agent.

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?

The schema already provides 100% coverage with detailed descriptions for all three parameters, including the requirement and error condition for voucherNumber. The tool description does not add new semantic information beyond what the schema already states, so the 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?

The description uses a specific verb ('Look up') and clearly identifies the resource ('bookkeeping vouchers') and the method ('by voucher number'). It explicitly distinguishes this tool from lexware_list_voucherlist by stating it is not a browsable collection, leaving no ambiguity about its purpose.

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 explicitly states when to use this tool (lookup by exact number) and when not to (browsing/filtering), directing users to lexware_list_voucherlist for those cases. It also warns about the required voucherNumber parameter and the HTTP 400 error, giving clear operational guidance.

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