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

Annotations already declare readOnly/idempotent/non-destructive, so safety is covered. The description adds genuinely non-structured behavior: the returned confirmation_token is valid for 15 minutes, and the tool operates only on an 'active chat case.' The 15-minute expiry is a material operational constraint an agent could not infer.

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 with no filler; the core behavior (check, return token, send nothing) is front-loaded and the WhatsApp exclusion is a brief trailing caveat.

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 documentation is unnecessary, yet the description still explains the sole meaningful output artifact (the token and its lifetime). Combined with annotations and full schema coverage, nothing needed to call this 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 both parameters are fully documented in the schema itself. The description reinforces that the message is the traveller's own words and implies the case must be an active chat case, but adds no format or validation detail beyond the schema. Baseline 3 applies.

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 ('checks a message ... and returns it with a confirmation_token') and immediately scopes it against the implicit write sibling with 'Nothing is sent.' An agent can distinguish this from sos_send_message 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?

'Nothing is sent' clearly frames this as a preparatory step preceding an actual send, and 'WhatsApp cases continue in WhatsApp' provides an explicit when-not condition. It stops short of naming the follow-up tool, leaving the agent to infer that sos_send_message is the next call.

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