add_reaction

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

The description only restates the basic action and adds no behavioral context beyond what annotations already convey. It does not mention idempotency, failure behavior, permissions, or side effects despite being a mutating open-world operation.

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 one short, direct sentence with no wasted words. It front-loads the core operation immediately.

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 three-parameter mutation with no parameter descriptions, this is thin. An agent gets no guidance on how to supply channel_id and message_ts correctly or what valid reaction values look like; the output schema helps only on the return side.

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 needed to compensate, but it only hints at the 'reaction' parameter. The meanings and formats of channel_id and message_ts are left entirely to inference from their names.

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 names a specific verb ('add') and a clear resource ('a reaction to a message'), which distinguishes it from message-posting tools like post_message. It does not explicitly differentiate itself from get_reactions, so it loses the top score.

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 intended use is implied: use this when you need to attach a reaction to a message. However, it provides no explicit guidance about when not to use it or how it relates to alternatives like get_reactions.

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