react_to_messageReact to a message with an emoji as the account. Use an empty emoji to remove the reaction.
React to a message with an emoji, as the account that received or sent it. An empty string removes the reaction.
| Name | Required | Description | Default |
|---|---|---|---|
| emoji | Yes | One emoji, such as a thumbs up. Empty removes the reaction. | |
| messageId | Yes | A wuapi message id (from list_messages, a send tool, or a webhook). |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already supply idempotentHint and non-destructive flags. The description adds genuinely useful behavior beyond them: an empty string removes the reaction, and the reaction is tied to the account identity. This is meaningful context an agent cannot infer from annotations alone.
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?
One compact, front-loaded sentence with no filler. It communicates the core action, the identity constraint, and the removal behavior in minimal space.
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?
For a two-required-parameter mutation with complete schema descriptions and helpful annotations, the description covers who can react and how to remove a reaction. Nothing essential for correctly invoking the tool is missing.
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 input schema provides 100% coverage of both parameters, including the empty-string removal behavior for emoji and the messageId source. The description reinforces this but does not add significant meaning beyond the schema.
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 and resource: 'React to a message with an emoji'. The account-scoping clause ('as the account that received or sent it') makes the action precise and differentiates it from generic send or reply tools.
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 gives clear context by explaining that the reaction is made as the account that received or sent the message, which is an implicit eligibility condition. It does not explicitly contrast with alternatives like reply_to_message, but the intended use is clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.