line_send_flex_message

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

No annotations are present, so the description carries the full burden. It discloses the basic action (sending) but omits behavioral traits like rate limits, permission requirements, or side effects beyond the implicit write operation.

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 sentence of 11 words, making it very concise. It directly states the action and target. However, it could include more details without becoming verbose, so it is slightly under-specified.

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 4 required parameters (some undocumented), no output schema, and no annotations, the description is incomplete. It lacks guidance on constructing the Flex Message, expected response format, or error handling, leaving significant gaps for an agent.

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 description coverage is 50%, with channel_access_token and to lacking descriptions. The tool description adds no parameter information beyond what exists in the schema. For the two undocumented parameters, the description fails to clarify their purpose.

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 it sends a Flex Message to a LINE user or group, specifying the type and target. However, it does not differentiate from sibling tools like line_send_message or line_broadcast, which also send messages.

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?

No guidance is provided on when to use this tool versus alternatives (e.g., line_send_message for text-only messages). Prerequisites or conditions for use are not mentioned.

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