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

annotations already declare readOnlyHint=true, so safety is covered; the description adds genuinely useful behavioral context by stating the return shape ('Returns the totals and the PDF as an embedded resource'), which matters because there is no output schema. It does not cover failure modes (e.g., document not found) or auth requirements.

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 compact sentences front-load the action, the scope and the identifier options, then disclose the return artifact. The trailing 'Számla Agent action-szamla_agent_pdf' is implementation detail that adds little for an agent, slightly diluting an otherwise tight entry.

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 three loosely-constrained parameters, no output schema and only readOnlyHint for annotations, the description supplies the missing pieces: which identifiers suffice and what comes back (totals plus an embedded PDF resource). Error behavior and any permission requirements remain unspecified, but nothing essential to a correct call 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% and each identifier is documented there, which sets a baseline of 3. The description goes beyond the schema by imposing a mutual-exclusivity rule ('give exactly one'), a constraint the schema does not encode (no oneOf, no required fields), and by clarifying that any of the three identifiers is acceptable.

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 uses a specific verb+resource ('Download the PDF of one issued document') and enumerates the acceptable identifiers, so the agent knows exactly what it retrieves. It does not explicitly contrast itself with the sibling szamlazz_get_invoice (data vs PDF), so sibling differentiation is only implied.

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?

'(give exactly one)' conveys an invocation constraint, and the identifier list implies when the tool applies, but there is no explicit when-to-use guidance or routing to alternatives such as szamlazz_get_invoice for non-PDF retrieval. Usage is implied rather than stated.

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