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

Annotations cover the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), and the description adds genuinely new context beyond them: the send is immediate and irreversible, and a draw admits only one bulk send. That irreversibility detail is exactly the kind of operational constraint 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 the action and its scope, then the irreversibility constraint, then the inputs. Every sentence carries information; no 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?

An output schema exists, so return values need not be described. The description covers scope, prerequisites, and the one-shot irreversible nature of the send, leaving only edge cases (error behavior, what happens on a second send) unstated.

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 67%, with locale and shareCode richly documented inline. The description adds provenance meaning for the two required parameters — that drawId and shareCode come from create_draw — which the schema does not state for drawId. Locale semantics are left entirely to the schema, so it is not a full 5.

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+resource ('Sends the email invitation to all participants of a draw') and scopes it to a draw created in this same conversation. It is clearly distinguishable from create_draw and get_group_share_message, one of which produces the identifiers this tool consumes.

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?

Explicitly names the prerequisite ('drawId and shareCode returned by create_draw') and the context constraint ('created in this same conversation'). It does not, however, name an alternative (e.g. get_group_share_message) or state when not to call it, so it stops short of full routing guidance.

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