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

Annotations declare readOnlyHint=false and idempotentHint=false, and the description explains exactly why: a temporary PDF is written to api.almmity.com, exposed via an unguessable link for one hour, then deleted. It also discloses the data-flow boundary (nothing sent to KSeF or third parties) and the auth exemption, all of which the 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?

Four short sentences, front-loaded with what it produces, then return value, then the privacy/lifecycle caveat. Every sentence carries distinct information; nothing is repeated or padded.

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?

An output schema exists, so return structure need not be spelled out, yet the description still flags that a viewer link is returned. Combined with the ephemeral-file lifecycle and no-auth notes, an agent has everything needed to call and explain this tool safely.

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?

Only one parameter, and schema coverage is 100% (it is documented as 'FA(3) invoice XML' with min/max length constraints). The description restates the input format but adds no syntax or size guidance beyond the schema, so the baseline 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 (Parse) and resource (FA(3) XML) plus the exact output content: parties, dates, net, VAT, gross, split payment, due date, bank account. That enumeration clearly separates it from sibling tools like validate_ksef_xml or generate_fa3_xml, which transform rather than summarize.

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 the use case (feed it an FA(3) XML and get a readable summary) and clarifies the no-API-key and no-KSeF-transmission conditions, but it never explicitly says when to pick this over validate_ksef_xml or generate_fa3_xml. Usage is inferable rather than stated.

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