Broadcast Flex Message

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

Annotations already mark destructiveHint true, so the description's warning ('sent to all users') reinforces this without adding new behavioral insights. The description does not disclose potential side effects like rate limits, quota usage, or message delivery guarantees, but the annotation reduces the burden. It adds some value by describing layout options.

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 three sentences: purpose, layout support, and warning. It is concise, front-loaded with the key action, and each sentence adds distinct value without redundancy.

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?

Given the extreme complexity of the input schema (nested objects, many optional structures) and no output schema, the description is too brief. It does not cover return values, error handling, or how to construct the message beyond layout types. The agent would need extensive external knowledge to use this tool effectively.

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 0% for the single parameter 'message', and the description only provides minimal guidance ('Supports bubble and carousel layouts'). It does not explain the structure or common properties of the message object, leaving the agent to parse the complex schema without added semantic help. The description fails to compensate adequately for the lack of schema descriptions.

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 clearly states the tool broadcasts a flex message to all LINE Official Account users, with specific verb (broadcast) and resource (flex message). It distinguishes from siblings like push_flex_message by noting 'all users' and from text messages by specifying 'flex message'. The mention of bubble and carousel layouts adds specificity.

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 explicitly states this sends to all users, which clearly distinguishes it from push tools that send to specific users. However, it does not explicitly mention when not to use it (e.g., for targeted messages) or provide alternatives. The warning about sending to all users adds appropriate context.

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