Add or remove a reaction

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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful context beyond them: the reaction is the bot's own, and emoji can be Unicode or name:id. It omits permission requirements, behavior when removing a reaction that does not exist, and whether the target message must be visible to the bot.

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?

Two short sentences, zero filler, with the core action front-loaded and the emoji format note immediately after. Nothing is repeated from the schema or annotations.

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 small four-parameter tool with annotations covering the safety profile and no output schema, the description is nearly sufficient: action, scope, and the trickiest parameter format are all covered. The remaining gap is the undocumented `remove` flag and any permission caveat, which is minor but not trivial for a mutation.

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 coverage is 50% – channel_id and message_id are documented, while emoji and remove are not. The description compensates for the emoji gap precisely by specifying the Unicode vs name:id format, but it never explains the `remove` boolean, whose default-false semantics must be inferred from the sentence.

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?

States a specific verb pair and resource: 'Add or remove the bot's reaction on a message.' The qualifier 'the bot's reaction' usefully scopes it to the bot's own reaction rather than other users'. It does not name or contrast with any sibling, but none of the listed siblings appear to handle reactions, so ambiguity is low.

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?

Usage is implied by the verb pair: add by default, remove when the removal mode is selected. There is no explicit statement of when to use this versus other message-manipulation tools (e.g. discord_admin_manage_message), no prerequisite/permission notes, and no explicit mapping of the `remove` flag to the remove behavior.

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