send_reaction

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

No annotations are provided, and the description only states the basic action. It fails to disclose that this tool mutates data (adds a reaction to an existing message), whether it is destructive, or any authorization requirements. The behavior beyond the action is opaque.

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 extremely concise (6 words) but under-specified. It lacks essential context, making it unhelpful despite its brevity. Conciseness should not sacrifice informativeness.

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 complex nested input schema and no output schema, the description is severely incomplete. It does not explain what the instance context is, how to obtain the message key, valid emojis, or the result of the operation. The tool's purpose is only vaguely conveyed.

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 description does not add meaning beyond what the input schema already provides. The schema describes 'instanceName' and 'reaction', but the nested 'key' object's properties (remoteJid, fromMe, id) are not explained. With 50% schema description coverage, the description should compensate but does not.

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: reacting to a message with an emoji. It is specific and unambiguous, but it does not differentiate from sibling tools like sending a sticker or media, which are distinct actions.

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 on when to use this tool versus alternatives like send_plain_text or mark_message_as_read. The usage is implied but not explicit, and no exclusions are mentioned.

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