Download an invoice as a PDF file using its invoice ID. Returns base64-encoded JSON to decode into a .pdf file.
Download an invoice as PDF (whmcs/download_invoice). InvAPI returns binary PDF; MCP returns JSON with encoding=base64 and data — decode to a .pdf file.
| Name | Required | Description | Default |
|---|---|---|---|
| invoice_id | Yes | Invoice number |
Changes observed during successful MCP inspections.
v1.0.3Input schema / properties / invoice_id / descriptionPrevious value: -"Номер инвойса"New value: +"Invoice number"v1.0.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
readOnlyHint and openWorldHint already tell the agent this is a safe read that reaches outside. The description adds genuinely useful behavior: the API returns binary PDF but MCP returns JSON with base64 encoding, a non-obvious transport difference. However it omits error behavior (e.g., what happens for an invalid or unauthorized invoice_id).
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?
Two dense sentences that front-load the action and include the endpoint and encoding detail. Efficient, though the parenthetical endpoint reference is slightly technical clutter.
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?
Complete for a single-param read tool: it says what is produced (PDF), how it arrives (base64 in JSON), and what to do with it. No output schema exists, and the description compensates by describing the return shape. Minor gap on failure modes.
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% and the single parameter has a clear description ('Invoice number'). The description adds no parameter-level semantics beyond the schema, so baseline 3 applies.
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 (download) and resource (invoice) with the output format (PDF). The sibling list contains get_invoice, get_invoices, and get_server_invoices, and this description makes clear this is the download-PDF variant rather than metadata retrieval.
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 use when a PDF is needed, but never explicitly contrasts with get_invoice/get_invoices to say when to prefer this over those. Usage context is inferable from the purpose, not stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.