Push Flex Message

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

With no annotations provided, the description carries the full burden of disclosing side effects. It mentions 'send' but does not describe potential outcomes like delivery failures, rate limits, or message validation issues, leaving the agent uninformed about behavioral consequences.

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 concise and to the point, using two short sentences that cover the primary action, target, and key input without any redundant or extraneous text.

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 context of many sibling push tools, the description fails to provide sufficient context for an agent to decide when to choose this Flex Message tool over alternatives. It also does not mention any output or return behavior, though the schema lacks an output schema, so that omission is partly mitigated.

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 already provides descriptions for all three parameters ('to', 'altText', 'contents'). The tool description adds the detail that 'contents' is a Flex container in JSON string form, but this is minimally additive since the schema's description already states the JSON nature and allowed values.

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 action ('Send') and the specific resource ('Flex Message'), which distinguishes it from sibling tools like push_text_message or push_image_message. The phrase 'rich layout' further clarifies the nature of the content.

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 does not explicitly state when to use this tool over the many sibling push options (e.g., text, image, sticker). It relies on the reader's understanding of Flex Messages, but offers no comparative guidance or conditions for selection.

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