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

Annotations are all false (non-read-only, non-idempotent, non-destructive), so the description carries some burden. It adds that the message text has a 500-character maximum and that the call returns 'the sent message details,' which is useful context. However, it does not disclose side effects like notifications to family members, error conditions, or the exact structure of the returned details.

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?

The description is a single clear sentence plus a compact Args/Returns block. Every word adds value, and the purpose is front-loaded; there is no redundant or filler content.

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?

For a one-parameter mutation with no output schema, the description gives the basic action and a return hint, but it omits prerequisites such as belonging to a family group, potential error conditions, and what fields the 'message details' actually include. This information would help an agent use the returned value for subsequent edit/delete operations.

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?

The input schema provides only a type and title for 'content' with no description, and schema coverage is 0%. The description compensates fully by stating 'Message text (max 500 characters),' which defines both the meaning and a constraint of the single parameter.

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?

The description uses a specific verb ('Send') and names a concrete resource ('a message in the family group chat'). This clearly distinguishes the tool from sibling actions like edit_family_chat_message, delete_family_chat_message, and list_family_chat_messages, and it is not a tautology of the title.

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?

The description provides no guidance on when to use this tool versus alternatives such as edit_family_chat_message or delete_family_chat_message. It only states the action itself, leaving the selection among siblings entirely to inference from the tool name and schema.

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