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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description usefully adds the key behavioral fact that nothing is actually sent and that output must be copied manually into a chat, which the annotations do not convey. It stops short of describing the message format or length.

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 tight sentences, front-loaded with the action and artefact, followed by localization scope and the sibling comparison. Every clause earns its place.

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-value detail is not needed. With annotations covering the safety profile and the description covering purpose, alternative and the no-side-effect guarantee, an agent has enough to call this correctly. Minor gap: drawName's meaning is left entirely to inference.

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% and the locale parameter already carries a very rich description (BCP 47 tags, brand mapping, precedence rules). The description restates the localization/brand behaviour but adds little syntax-level detail, and drawName has no schema description at all while the description never mentions it. 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 artefact: 'Generates a ready-to-paste WhatsApp/Telegram message announcing a freshly created draw.' It also distinguishes itself from the sibling send_invitations_email by framing itself as the no-email alternative, so an agent can tell the two apart without opening either 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?

Explicitly names the alternative and the selecting condition: 'It is the alternative to send_invitations_email for sharing without emails: nothing is sent.' The when/when-not is unambiguous.

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