WhatsApp MCP Server

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

No annotations are provided, so the description carries the full burden. It discloses key behavioral traits: launching a browser, connecting to WhatsApp Web, and the login/verification functionality. However, it lacks details on error handling, timeouts, authentication persistence, or what 'verify' entails. For a tool with no annotations, this is adequate but leaves gaps in operational context.

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 two sentences, front-loaded with the core action ('Launch browser and connect to WhatsApp Web'), followed by usage guidance. Every word earns its place, with no redundancy or fluff. It efficiently communicates essential information without unnecessary elaboration.

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?

Given the tool's complexity (browser automation with login/verification), no annotations, and no output schema, the description is minimally complete. It covers the purpose and usage but lacks details on behavioral outcomes, error conditions, or what success/failure looks like. For a tool with this functionality, more context would be beneficial, but it meets basic requirements.

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 description coverage is 100%, so the schema already documents the single parameter 'headless' with its type, default, and description. The description adds no parameter-specific information beyond what's in the schema. With 0 parameters requiring semantic explanation from the description, a baseline of 4 is appropriate as the schema suffices.

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 tool's purpose with specific verbs ('Launch browser', 'connect to WhatsApp Web') and resources ('browser', 'WhatsApp Web'), and distinguishes it from siblings by focusing on connection/login rather than chat listing or messaging. It explicitly mentions the dual use case of 'login or verify if you are already logged in', making the purpose unambiguous.

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 provides explicit guidance on when to use this tool: 'Use this to login or verify if you are already logged in.' It distinguishes from sibling tools (list_chats, send_message) by implying this is a prerequisite step for accessing WhatsApp functionality, though it doesn't explicitly name alternatives. The guidance is clear and actionable.

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