beel_get_invoice_preview

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

Annotations indicate readOnlyHint=true, idempotentHint=true, and openWorldHint=true. The description adds valuable behavior: the image is generated and cached on first request, so later calls return cached images; the URL expires in five minutes; and only GET is allowed. This goes beyond the annotations and helps the agent understand caching and expiry implications. The endpoint is also provided, which aids debugging and understanding. No contradictions.

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 concise and front-loaded with the key info: what it returns, the format, and the purpose. The endpoint is appended. There is minimal redundancy, though the endpoint could be considered extra but useful. The description is not overly verbose and avoids 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 the tool's simplicity, the description covers the essential aspects: purpose, output type, caching behavior, URL expiry, and HTTP method restrictions. It does not mention what happens if the invoice doesn't exist or is not accessible, but annotations and schema cover some error behavior. The output schema is absent, so the description does not need to describe return values. Overall, sufficiently complete for an agent to call correctly.

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 100%, so the description does not need to detail parameters. However, the description does not add extra semantic value beyond what the schema already provides. The schema for company_id is already detailed (explaining the NIF context, auth, and 403 behavior). The description simply mentions the endpoint, which is redundant with the schema's param names. Thus, the description adds no incremental value for parameters; 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 states a clear purpose: returns a temporary pre-signed URL to a preview image (WebP) of an invoice for inline rendering. It includes the endpoint, distinguishing it from related tools like beel_get_invoice_pdf and beel_download_representation_document. It clearly names the resource and the specific output type, leaving no ambiguity about what the tool does.

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 implies usage for inline preview rendering and notes that the URL is only for GET. It does not explicitly compare with alternatives like beel_get_invoice_pdf, but the mention of 'preview image' and 'inline rendering' gives clear context. The sibling list includes get_invoice_pdf, so a brief comparison would be helpful, but the context is strong enough.

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