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

With no annotations, the description carries the full burden. The "cheap first step" phrasing usefully signals low cost and implies a non-mutating inspection, but it does not state read-only behavior explicitly, permission requirements, or what the response contains.

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 tight sentences: the purpose first, then the actionable sequencing hint. No filler, and the highest-value guidance (use this first) is placed after the purpose but still front-loaded.

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?

There is no output schema, so the description profitably enumerates the return fields (format, syntax, profile/customization, country standard). It stops short of describing the response shape or behavior on unrecognized input, which leaves a small gap for a detection tool.

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% and both parameters (content, content_base64) are fully documented in the schema, including which formats each accepts. The description adds no syntax or format guidance beyond that, so the 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 precise verb (Identify) and the exact attributes returned (format, syntax, profile/customization, country standard) for a named resource (e-invoice file). This makes it clearly distinguishable from siblings like validate_invoice, parse_invoice, or render_invoice_pdf.

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?

"Cheap first step before validating" gives explicit sequencing guidance, implicitly routing agents to run this before validate_invoice. It lacks an explicit when-not statement or a named alternative tool, but the context is clear.

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