line_send_flex_message

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

No annotations are provided, so the description should disclose side effects or constraints. It only states a send action, without noting that a message is posted to a user's line chat, that it may be subject to rate limits, or what happens on failure. The description does not convey that this is a destructive action (sending a message).

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 10-word sentence that instantly conveys the tool's core function. It uses active voice and places the verb first, making it efficient and easy to scan.

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?

The tool has 4 required parameters and no output schema, yet the description provides only a one-line summary. It omits important context such as return behavior, error states, prerequisites for the Flex Message format, and any limitations. Given the lack of annotations, this is insufficient for an agent to reliably invoke the tool.

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 schema has descriptions for alt_text and contents only. The description does not add meaning for channel_access_token or to, which remain unannotated in schema. It does not specify that 'to' should be a user or group ID. The description adds the general context of 'user or group', but does not map to specific parameters.

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 explicitly states the action 'Send', the resource 'rich Flex Message', and the recipient scope 'to a LINE user or group'. This clearly distinguishes the tool from its similar sibling 'line_send_message' which likely sends plain text.

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 the sibling tool 'line_send_message'. It does not mention prerequisites, such as having a valid Flex Message structure, or when not to use it.

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