proforma_invoices_pdf

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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds real value beyond that by disclosing the return payload shape ("base64-encoded binary data") and a licensing constraint (Pro plan), which annotations cannot express.

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 short sentences, front-loaded with the action and result, with the prerequisite last. Nothing is wasted and there is no restating of the title.

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 binary-download tool with no output schema, mentioning base64 encoding is important and covers the main return-value question. But the description omits whether the proforma must be in a particular state to render a PDF, how errors surface, and any size/streaming caveats—gaps an agent may hit at runtime.

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 uuid and companyId are already self-documenting, and the description adds nothing about their meaning or interaction (e.g., how companyId override affects the lookup). This is the expected baseline 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 description pairs a specific verb ("Download") with a precise resource ("PDF of a proforma invoice"), which is clearly distinguishable from proforma_invoices_get (metadata) and proforma_invoices_list. It stops short of naming those siblings explicitly, so differentiation is implied rather than stated.

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 plan prerequisite ("Requires Pro plan") tells the agent a precondition for calling, and "Download the PDF" implies the retrieve-the-rendered-document use case. However, there is no explicit when-to-use guidance versus proforma_invoices_get, nor any exclusion or failure condition guidance.

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