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

Annotations only declare destructiveHint=true; the description reinforces this with 'Cannot be undone' and clarifies it emails real people from the connection's contacts, which is meaningful beyond the annotation. Missing are failure modes (invalid recipient, already-delivered invoice) and whether the response reports delivery status, so it stops at 4.

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 sentences, front-loaded with the 'WRITE, SENDS EMAIL' safety marker, followed by scope, irreversibility, and the API route. No padding.

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 7 params at full schema coverage, no output schema, and a sparse annotation set, the description covers purpose, mode selection, and irreversibility adequately. It could say more about what happens on partial input (e.g. recipients without subject/message) or the return shape of a delivery call, which keeps it at 4.

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%, including the confirm const, hash_key format note, and the custom-delivery grouping rules, so the structured data already carries the semantics. The description's mention of 'custom recipient/subject/message' largely restates the schema's own mode documentation rather than adding new meaning, so the baseline 3 is appropriate.

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 ('email an invoice to the client') and immediately discloses the two delivery modes (default template to the connection's contacts vs. custom recipient/subject/message), plus the underlying endpoint POST /invs/{hash_key}/deliver. An agent can distinguish this from hiveage_send_estimate and hiveage_send_invoice_reminder without opening the schema.

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?

Clear about the two calling modes (omit recipients for the default template, supply custom recipients/subject/message otherwise) and warns 'Cannot be undone', which sets the bar for when to use it. It does not name alternatives such as hiveage_send_invoice_reminder or state when-not-to-use (e.g. invoice already sent / unpaid), so it falls short of a 5.

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