react

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

No annotations are provided, so the description carries the full burden. It adds useful context about Unicode vs. custom emoji syntax, but does not disclose whether the reaction is additive, if permissions are required, or any error behavior beyond the implied mutation.

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 two sentences, front-loaded with the primary purpose and immediately useful syntax detail. Every word earns its place with no redundancy.

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?

The tool is simple and the description covers the core action and emoji format, but it omits any error handling, success/failure behavior, or whether custom emoji must belong to the same server. Given the lack of annotations and output schema, a bit more context would make it fully 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?

Schema description coverage is 0%, so the description must explain parameters. It only explains the 'emoji' parameter format; 'chat_id' and 'message_id' are left implicit by name. This is a significant gap given the schema provides no descriptions.

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 an emoji reaction') and resource ('Discord message'), with specific syntax details for Unicode and custom emoji that distinguish it from sibling messaging tools like reply and send_message.

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 purpose implies usage for reactions rather than sending or replying, but the description does not explicitly state when to use this tool over alternatives or provide any exclusions. It relies on the reader to infer from the verb 'react'.

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