messages_react

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

Annotations already declare readOnlyHint=false, destructiveHint=true, and openWorldHint=true, so the safety profile is covered. The description adds that the reaction 'reaches other people on the platform' and advises confirming with the user, which is useful, but the 'deletes, or redirects data' clause is generic boilerplate not specific to this tool.

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 purpose is front-loaded in the first line, which is good. However, the boilerplate caution and the endpoint/gRPC/socket metadata line do not earn their place for an agent choosing a tool.

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 4-parameter mutation tool with no output schema, the description leaves parameter meaning entirely undocumented and substitutes a generic warning in place of concrete behavior. Annotations cover safety, but the callable details an agent needs are missing.

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?

All four required parameters (channelId, chatId, messageId, emoji) have 0% schema description coverage, and the description adds no semantics about them — not even the accepted emoji format or ID relationships. It does not compensate for the coverage gap.

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 ('React to a message with an emoji') and clearly reads as distinct from siblings like messages_remove_reaction or messages_send. An agent can identify the operation without opening the schema.

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?

No guidance on when to react vs. alternatives such as messages_remove_reaction or messages_reply. The second line is a generic caution template, not usage direction, so the agent gets no routing help.

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