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

Annotations already cover safety (readOnly, idempotent, non-destructive), and the description adds state-dependent behavior: drafts come back stamped DRAFT, issued invoices additionally carry pdf_url, and pdf_base64 is large and issued-only. The unauthenticated, one-click nature of pdf_url is disclosed, which is important operational context.

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 output shape is front-loaded and every sentence is actionable, though the prose is conversational and the with_pdf fallback is explained twice across description and schema. Slightly tighter phrasing would eliminate the only redundancy.

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 fully carries the return contract — page image, pdf_url after issue, optional pdf_base64 — plus the pre/post-issue distinction an agent needs to call it correctly. Nothing material 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 coverage is 100%, so page, with_pdf, and invoice_id are already documented. The description restates the with_pdf fallback rationale and the 1-based page convention, adding only mild emphasis rather than new meaning. Baseline 3 applies when the schema carries the parameter burden.

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 first sentence names the concrete outputs — a rendered page image and, once issued, a direct PDF download link — which immediately separates it from the JSON-returning solo_get_invoice. Verb (render/fetch document) and resource (invoice document) are unambiguous.

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?

Explicit lifecycle guidance: call before issuing to inspect the DRAFT-stamped render, call again after issue to hand back pdf_url. It also states when NOT to use a mode ("with_pdf=true exists only as a fallback") and warns against relaying bytes, which routes the agent away from wrong behaviors.

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