mcp-whatsapp

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

The description adds valuable behavioral context beyond annotations: it explains that empty emoji clears existing reactions, which is crucial operational knowledge. Annotations already indicate this is destructive and not idempotent, but the description provides specific behavioral details about reaction management that annotations don't cover.

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 perfectly concise with two sentences that each serve distinct purposes: the first states the core function, the second explains a critical behavioral nuance. Every word earns its place, and the structure is front-loaded with the primary purpose.

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 destructive operation with no output schema, the description provides good context about the emoji clearing behavior. However, it doesn't mention error conditions, permission requirements, or what happens when reacting to one's own messages versus others'. The annotations cover safety aspects, but more operational context would be helpful.

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?

With 100% schema description coverage, the schema already documents all parameters thoroughly. The description adds minimal value beyond the schema by mentioning the emoji parameter's special behavior with empty strings, but doesn't provide additional semantic context for the other three parameters.

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 specific action ('React to a message') and resource ('a message'), distinguishing it from siblings like send_message or edit_message. It also uniquely mentions the ability to clear reactions, which sets it apart from other messaging tools.

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 description implies usage for reacting to messages, but doesn't explicitly state when to use this versus alternatives like send_message or edit_message. It mentions clearing reactions as a specific use case, but lacks broader contextual guidance about when reactions are appropriate versus other message types.

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