discord_add_reaction

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

Annotations already declare idempotentHint=true, and the description reinforces this with a concrete explanation of the idempotent behavior. It adds valuable context beyond the annotations by stating the required permissions and that the action is performed as the bot. There is no contradiction with any annotation.

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?

Four short sentences, each carrying distinct useful information: action, permissions, undo path, and idempotency. The core action is front-loaded, and there is no redundant or filler wording.

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 simple three-parameter action with no output schema, the description covers the essential context: what it does, what permissions are needed, how to undo it, and its idempotent nature. The schema already documents parameter formats, so nothing important is missing for an agent to invoke this correctly.

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 schema covers all parameters with descriptions, including emoji format ('name:id' for custom emojis) and snowflake patterns for IDs. The description adds little parameter-specific meaning beyond 'single emoji reaction', but with 100% schema coverage, the baseline of 3 is appropriate.

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 and resource: adds a single emoji reaction to a message as the bot. The phrase 'as the bot' clarifies the acting identity, and 'single emoji reaction' disambiguates it from broader message actions. This clearly distinguishes it from related siblings like discord_remove_reactions and discord_get_reactions.

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?

Provides explicit permission requirements (Add Reactions and Read Message History), which tells the agent when the tool is usable. It also names discord_remove_reactions as the undo alternative, giving clear routing for the reverse operation. It does not discuss choosing this over sending an emoji in a message, but that is not a strong competing alternative.

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