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

The description adds real behavior beyond destructiveHint=true: 'The e-mail cannot be recalled' flags irreversibility, and the omitted-fields fallback explains a non-obvious side effect (re-sending with prior settings). It does not cover auth/permission needs or rate limits, but for a send action the key behavioral risk is disclosed and consistent with the annotation.

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 sentences, each earning its place: the core action first, then the optional-parameter behavior, then the irreversibility warning, with the internal action name appended. Tightly front-loaded with zero filler.

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 no output schema and only one required parameter, the description covers the action, the fallback behavior, and the irreversibility warning. It leaves minor gaps such as whether the receipt must exist in the account and what a success response looks like, but nothing an agent needs to call it correctly 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%, so the baseline is 3, but the description adds meaning the schema lacks: that omitting email/subject/body/reply_to is not an error but triggers a re-send using the previous e-mail's configuration. That is a semantic behavior of the optional parameters documented nowhere in the schema.

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 and resource ('E-MAILS an already issued receipt (PDF) to a customer'), including the scope qualifier 'already issued' and the underlying Számla Agent action name. It is clearly distinguishable from siblings such as szamlazz_get_receipt, szamlazz_create_receipt, and szamlazz_reverse_receipt.

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?

Gives a clear operational condition: supplying no e-mail fields causes the vendor to re-send using the earlier e-mail's settings, and states the prerequisite that the receipt is already issued. It does not name alternative tools or explicitly state when not to use it, but the usage context is unambiguous.

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