add_reaction

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

No annotations are provided, so the description carries full responsibility for behavioral disclosure. The description merely states the action without mentioning potential side effects, required permissions, error conditions, or whether the reaction is partial or complete. This is similar to other minimally transparent mutation tools.

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 sentence that is perfectly concise and front-loaded. It contains no redundant information and effectively communicates the core purpose.

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 tool's simplicity and the complete parameter schema, the description is mostly adequate. However, with no output schema and no mention of return values or failure behavior, an agent might be uncertain about the result of a successful call, leaving some gaps in completeness.

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 descriptions for all three parameters (channel_id, message_id, emoji) with 100% coverage. The description adds no additional parameter meaning, so it relies entirely on the schema to define parameter semantics.

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 ('Add') and the resource ('an emoji reaction') with a specific target ('to a message'). This is a distinct operation compared to sibling tools like pin_message or send_message, making the purpose unambiguous.

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?

While the description does not explicitly state when to use this tool over alternatives, the tool's name and description make its usage obvious. No exclusions, prerequisites, or alternative tool references are mentioned, but the context is clear enough for an agent to infer when to invoke it.

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