React To Message

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

Annotations already indicate a non-readOnly side-effecting operation, and the description is consistent with that. However, the description adds no additional behavioral context such as whether the reaction is attached to a specific message, how failures are handled, or potential side effects beyond the reaction itself. It does not contradict annotations.

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, tightly written sentence that lists the reaction types and conveys the core action without extraneous content. It is well-structured and easy to parse.

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?

This tool has no output schema and minimal annotations, so the description must carry the full explanation. It fails to explain that reacting to a message requires a target message, how to identify it, or whether the reaction applies to the most recent message. This is a significant gap for correct invocation; the description is too sparse to be complete.

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 covers both parameters with descriptions, but the tool description adds no meaning beyond repeating the enum values already present in the schema. Critically, the schema includes only chatId and type, lacking a message identifier, and the description does not clarify how a target message is selected—rendering parameter semantics incomplete.

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 states a specific verb ('Send') and resource ('tapback reaction') and lists the allowed reaction types, making the core purpose clear. However, it does not explicitly distinguish itself from the sibling tool 'send-message', and notably omits any mention of which message the reaction is applied to (no messageId in the schema).

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?

There is no guidance on when to use this tool versus alternatives like 'send-message' or 'read-messages'. No prerequisites (e.g., existence of a message to react to) or exclusions are provided, leaving the agent to infer usage context.

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